Daily Science: Epidemiology

1 June


Dora AV, Winnett A, Jatt LP, et al. Universal and Serial Laboratory Testing for SARS-CoV-2 at a Long-Term Care Skilled Nursing Facility for Veterans – Los Angeles, California, 2020. MMWR Morb Mortal Wkly Rep. 2020 May 29;69(21):651-655. PubMed: https://pubmed.gov/32463809. Full-text: https://doi.org/10.15585/mmwr.mm6921e1

Again and again: Test them all, immediately. On March 28, 2020, two residents of a long-term care skilled nursing facility in Los Angeles had positive test results. From March 29-April 23, all residents, regardless of symptoms, underwent serial (approximately weekly) nasopharyngeal PCR testing. 8/99 (19%) residents and 8/136 (6%) staff members had positive test results. 14/19 residents were asymptomatic at the time of testing. Among these, eight developed symptoms 1-5 days after specimen collection and were later classified as presymptomatic.


Looi MK. Covid-19: Japan ends state of emergency but warns of “new normal”. BMJ. 2020 May 26;369:m2100. PubMed: https://pubmed.gov/32457055. Full-text: https://doi.org/10.1136/bmj.m2100

Japan has done a good job. This article explains why. Public adherence to the rules, along with cluster tracing and a ban on mass gatherings, seems to have achieved success in bringing the outbreak under control, alongside widespread mask use and hygiene being a normal part of Japanese etiquette. Japan has ended its state of emergency a week after its new infections fell below 50 a day.


2 June


Lee H, Lee H, Song KH, et al. Impact of Public Health Interventions on Seasonal Influenza Activity During the SARS-CoV-2 Outbreak in Korea. Clin Infect Dis. 2020. PubMed: https://pubmed.gov/32472687. Full-text: https://doi.org/10.1093/cid/ciaa672

Efforts to activate high level national response not only led to a decrease in COVID-19, but also a substantial decrease in seasonal influenza activity. During the period of enforced social distancing from week 9 to 17 of 2020 in Korea, influenza hospitalization cases were 11.9-26.9-fold lower compared with previous seasons. This is good news, because nobody needs influenza.



Ragan I, Hartson L, Pidcoke H, Bowen R, Goodrich R. Pathogen reduction of SARS-CoV-2 virus in plasma and whole blood using riboflavin and UV light. PLoS One. 2020 May 29;15(5. PubMed: https://pubmed.gov/32470046. Full-text: https://doi.org/10.1371/journal.pone.0233947. eCollection 2020

Plasma and whole blood units infected with SARS-CoV-2 underwent treatment with riboflavin and UV light. Riboflavin and UV light effectively reduced the titer of SARS-CoV-2 to the limit of detection in human plasma and by 3.30 ± 0.26 on average in whole blood. This is good news, because these treatments may reduce blood-borne pathogens in high-risk settings while maintaining blood product quality.


Nagano T, Arii J, Nishimura M, et al. Diligent medical activities of a publicly designated medical institution for infectious diseases pave the way for overcoming COVID-19: A positive message to people working at the cutting edge. Clin Infect Dis. 2020 May 31. PubMed: https://pubmed.gov/32474577. Full-text: https://doi.org/10.1093/cid/ciaa694

Of 509 medical staff members working to treat COVID-19 patients at the Hyogo Prefectural Kakogawa Medical Center, a large medical institution for infectious diseases in Japan (mean number of hospitalized COVID-19 patients was 20), none had IgG antibodies for SARS-CoV-2 on May 1-8. This is good news, because results show that standard preventive measures against infectious diseases can prevent SARS-CoV-2 exposure in medical staff.


3 June


Davies NG, Kucharski ADJ, Eggo RM, et al. Effects of non-pharmaceutical interventions on COVID-19 cases, deaths, and demand for hospital services in the UK: a modelling study. Lancet, June 02, 2020. Full-text: https://doi.org/10.1016/S2468-2667(20)30133-X

Herd immunity? Forget it. Using a stochastic age-structured transmission model to explore a range of intervention scenarios, tracking 66 million people in England, Wales, Scotland, and Northern Ireland, the authors projected a median unmitigated burden of 23 million (95% prediction interval 13–30) clinical cases and 350,000 deaths (170,000–480, 000) due to COVID-19 in the UK by December, 2021. Bad news because extreme measures are probably required to bring the epidemic under control.


4 June


Davies NG, Kucharski ADJ, Eggo RM, et al. Effects of non-pharmaceutical interventions on COVID-19 cases, deaths, and demand for hospital services in the UK: a modelling study. Lancet, June 02, 2020. Full-text: https://doi.org/10.1016/S2468-2667(20)30133-X

Herd immunity? Forget it. Using a stochastic age-structured transmission model to explore a range of intervention scenarios, tracking 66 million people in England, Wales, Scotland, and Northern Ireland, the authors projected a median unmitigated burden of 23 million (95% prediction interval 13–30) clinical cases and 350,000 deaths (170,000–480, 000) due to COVID-19 in the UK by December, 2021. Bad news because extreme measures are probably required to bring the epidemic under control.


7 June


Li Z, Chen Q, Feng L, et al.  Active case finding with case management: the key to tackling the COVID-19 pandemic. The Lancet, June 4, 2020. https://doi.org/10.1016/S0140-6736(20)31278-2

Learning from China. Case finding and management, with identification and quarantine of close contacts: the authors describe the next steps planned in China following the containment effort.


8 June


Xu X, Sun J, Nie S, et al. Seroprevalence of immunoglobulin M and G antibodies against SARS-CoV-2 in China. Nat Med. 2020 Jun 5. PubMed: https://pubmed.gov/32504052. Full-text: https://doi.org/10.1038/s41591-020-0949-6

To estimate the cumulative prevalence, authors evaluated IgM and IgG antibodies in 17,368 individuals from Wuhan, China. The seropositivity in Wuhan was low, varying between 3.2% and 3.8% in different sub-cohorts. As seen in other studies, an early and a higher level of IgG response was observed, compared to IgM.


Graham N, Junghans C, Downes R, et al. SARS-CoV-2 infection, clinical features and outcome of COVID-19 in United Kingdom nursing homes. J Infect. 2020 Jun 3:S0163-4453(20)30348-0. PubMed: https://pubmed.gov/32504743. Full-text: https://doi.org/10.1016/j.jinf.2020.05.073

Outbreak investigation involving 394 residents and 70 staff in 4 nursing homes in central London. Overall, 26% of residents died over a two-month period. Systematic testing identified 40% of residents as positive for SARS-CoV-2 and of these, 43% were asymptomatic and 18% had only atypical symptoms during the two weeks prior to testing. Of note, this was also true of many residents in the days leading up to death indicating that even in severe COVID-19, fever and cough were commonly absent. 4% of asymptomatic staff also tested positive.


9 June


Flaxman S, Mishra S, Gandy A, et al. Estimating the effects of non-pharmaceutical interventions on COVID-19 in Europe. Nature. 2020 Jun 8. PubMed: https://pubmed.gov/32512579. Full-text:  https://doi.org/10.1038/s41586-020-2405-7 l (Important)

This world-leading group of epidemiologists and statisticians estimated the total infection rates across 11 European countries. Main results: between 12 and 15 million individuals have been infected with SARS-CoV-2 up to May 4th, representing between 3.2% and 4.0% of the population. Percentages of total population infected were for Austria 0.76% (0.59% – 0.98%), Belgium 8.0 % (6.1% – 11%), Denmark 1.0% (0.81% – 1.4%), France 3.4% (2.7% – 4.3%), Germany 0.85% (0.66% – 1.1%), Italy 4.6% (3.6% – 5.8%), Norway 0.46% (0.34% – 0.61%), Spain 5.5% (4.4% – 7.0%), Sweden 3.7% (2.8% – 5.1%), Switzerland 1.9% (1.5% – 2.4%) and United Kingdom 5.1% (4.0% – 6.5%). Results also showed that major non-pharmaceutical interventions and lockdown in particular have had a large effect on reducing transmission.


Deng X, Gu W,Federman S, et al. Genomic surveillance reveals multiple introductions of SARS-CoV-2 into Northern California. Science 08 Jun 2020. Full-text: https://doi.org/10.1126/science.abb9263

Detective work, analysing the genomic epidemiology of SARS-CoV-2 in Northern California from late January to mid-March 2020, using samples from 36 patients spanning 9 counties and the Grand Princess cruise ship. Phylogenetic analyses revealed the cryptic introduction of at least 7 different SARS-CoV-2 lineages into California, including epidemic WA1 strains associated with Washington State, with a lack of predominant lineage, and limited transmission between communities.


10 June


Payne DC, Smith-Jeffcoat SE, Nowak G, et al. SARS-CoV-2 Infections and Serologic Responses from a Sample of U.S. Navy Service Members — USS Theodore Roosevelt, April 2020. MMWR Morb Mortal Wkly Rep. ePub: 9 June 2020. Full-text: https://www.cdc.gov/mmwr/volumes/69/wr/mm6923e4.htm

In late March 2020, a large outbreak on the aircraft carrier USS Theodore Roosevelt was characterized by widespread transmission with relatively mild symptoms and asymptomatic infection among mostly young, healthy adults with close, congregate exposures. One fifth of infected participants reported no symptoms. Preventive measures, such as using face-coverings and observing social distancing, reduced risk for infection: among 382 service members, those who reported taking preventive measures had a lower infection rate than did those who did not report taking these measures (e.g., wearing a face-covering, 56% versus 81%; avoiding common areas, 54% versus 68%; and observing social distancing, 55% versus 70%, respectively).


11 June


ECDC Public Health Emergency Team, Danis K, Fonteneau L, et al. High impact of COVID-19 in long-term care facilities, suggestion for monitoring in the EU/EEA.  May 2020. Eurosurveillance, Volume 25, Issue 22, 04/Jun/2020 Article. Full-text: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.22.2000956

Residents in long-term care facilities contribute 30–60% of all COVID-19 deaths in many European countries. This article provides an overview of the importance of surveillance and infection prevention and control measures, in order to identify clusters early, decrease the spread within and between facilities and reduce the size and severity of outbreaks.


Enserink M. Coronavirus rips through Dutch mink farms, triggering culls to prevent human infections. Science Mag 2020, June 9. Full-text: https://www.sciencemag.org/news/2020/06/coronavirus-rips-through-dutch-mink-farms-triggering-culls-prevent-human-infections

Sad story on several outbreaks at Dutch mink farms. That mink are susceptible wasn’t a surprise, because they are closely related to ferrets. Once COVID-19 reaches a farm, the virus appears to spread like wildfire, even though the animals are housed in separate cages. The government decided to cull thousands of animals because the problem could become bigger in the months ahead.


12 June


Furuse Y, Sando E, Tsuchiya N, et al. Clusters of Coronavirus Disease in Communities, Japan. January-April 2020. Emerg Infect Dis. 2020 Jun 10;26(9). PubMed: https://pubmed.gov/32521222. Full-text: https://doi.org/10.3201/eid2609.202272

Bye, bye, karaoke. The Japanese authors defined a cluster as > 5 cases with primary exposure reported at a common event or venue, excluding within-household transmissions. In total, 61 COVID-19 clusters were found in various communities in the country: 18 (30%) in healthcare facilities; 10 (16%) in care facilities of other types, such as nursing homes and day care centers; 10 (16%) in restaurants or bars; 8 (13%) in workplaces; 7 (11%) in music-related events, such as live music concerts, chorus group rehearsals, and karaoke parties; 5 (8%) in gymnasiums; 2 (3%) in ceremonial functions; and 1 (2%) in transportation-related incident in an airplane. Of note, 41% of probable primary case-patients were pre-symptomatic or asymptomatic at the time of transmission. 45% had cough. Many clusters were associated with heavy breathing in close proximity.


Stringhini S, Wisniak A, Piumatti G, et al. The Lancet, June 11, 2020. Seroprevalence of anti-SARS-CoV-2 IgG antibodies in Geneva, Switzerland (SEROCoV-POP): a population-based study. Full-text: https://doi.org/10.1016/S0140-6736(20)31304-0

Geneva was a COVID-19 hot spot in Switzerland (5000 cases over < 2,5 months in half a million people). Authors performed 5 consecutive weekly sero-surveys among 2,766 randomly selected participants from a previous population-representative survey, and 1,339 household members aged 5 years and older. Each participant was tested for anti-SARS-CoV-2-IgG antibodies. Seroprevalence increased from about 5% to about 11%. Of note, young children (5–9 years) and older people (≥ 65 years) had significantly lower seroprevalence than the other age groups. Authors estimated that there were 11 infections for every COVID-19 confirmed case.


13 June


Walker PG, Whittaker C, Watson OJ, et al. The impact of COVID-19 and strategies for mitigation and suppression in low- and middle-income countries. Science 12 Jun 2020. Full-text: https://DOI.ORG/10.1126/science.abc0035

An in-depth analysis of the potential impact of the pandemic in low- and middle-income countries (LMIC). The analysis gives insight into how differences in demography, social structure and health care availability and quality combine and potentially influence the impact of measures that can help reduce the spread of the virus. However, the bottom line is: We don’t know yet. On one hand, we have an overall younger population and a shorter time for lockdown measures to be in place in LMIC. On the other hand, there is a higher burden of infectious diseases such as AIDS and TB already, and of poverty-related determinants of poorer health outcomes such as malnutrition. There is also a more persistent spread to older age categories (higher levels of household-based transmissions) and poorer quality health care and lack of health care capacity.


Oreshkova N, Molenar RJ, Vremen S. SARS-CoV-2 infection in farmed minks, the Netherlands, April and May 2020. Eurosurveillance 2020, June 11. Volume 25, Issue 23. Full-text: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.23.2001005

Despite a law approved by the Dutch parliament in 2012 that will ban mink farming as of 2024 for ethical reasons, there are still around 125 mink farms in the Netherlands, with an average of 5,000 female breeding animals. In 2019, 4 million minks were “produced”. This article describes several outbreaks on these farms. Detection of viral RNA in the airborne inhalable dust clearly suggests dust and/or droplets as means of transmission between the minks and occupational risk of exposure for the workers on the farms. On 3 June, the Dutch Ministry of Agriculture decided to cull all minks of SARS-CoV-2-infected farms, starting on 5 June. This may be the right time to speed up the final ban.


15 June


Mubarak N, Zin CS. Religious tourism and mass religious gatherings – The potential link in the spread of COVID-19. Current perspective and future implications. Travel Med Infect Dis. 2020 Jun 9;36:101786. PubMed: https://pubmed.gov/32531422. Full-text: https://doi.org/10.1016/j.tmaid.2020.101786

Important comment on mass religious gatherings. The authors recommend restrictions on the entry of Hajj pilgrims who are from epicentres and hotspots, from countries with suboptimal disease surveillance systems or with inadequate quarantine and diagnostic infrastructure for returning pilgrims who are over 50 years old or suffer from chronic disease, ie patients with diabetes and cardiovascular complications. Saudi Arabia needs to deploy a pre-emptive approach. We’ll see whether this is feasible.


Habib H. Has Sweden’s controversial covid-19 strategy been successful? BMJ 2020; 369. Full-text: https://doi.org/10.1136/bmj.m2376

Probably not. Some thoughts on Sweden’s controversial decision not to lock down the country. They are still far away from herd immunity (an ongoing nationwide study on 20 May found that just 7.3% of Stockholm residents had developed antibodies) and the death toll is immense.


Okell LC, Verity R, Watson OJ, et al. Have deaths from COVID-19 in Europe plateaued due to herd immunity? Lancet. 2020 Jun 11:S0140-6736(20)31357-X. PubMed: https://pubmed.gov/32534627. Full-text: https://doi.org/10.1016/S0140-6736(20)31357-X

No. Epidemiological data suggest that no country has yet seen infection rates sufficient to prevent a second wave of transmission, should controls or behavioural precautions be relaxed without compensatory measures in place.


16 June


Stoke EK, Zambrano LD, Anderson KN. Coronavirus Disease 2019 Case Surveillance — United States, January 22–May 30, 2020. MMWR June 15, 2020. Full-text: https://www.cdc.gov/mmwr/volumes/69/wr/mm6924e2.htm

A detailed picture of the epidemic in the US. This report describes demographic characteristics, underlying health conditions, symptoms, and outcomes among 1,320,488 laboratory-confirmed COVID-19 cases individually reported to CDC during January 22–May 30, 2020. Some key messages: Overall, 14% of patients were hospitalized, 2% were admitted to an intensive care unit (ICU), and 5% died. Among cases with known race and ethnicity, 33% of persons were Hispanic, 22% were black, and 1.3% were non-Hispanic American Indian or Alaska Native. These findings suggest that persons in these groups, who account for 18%, 13%, and 0.7% of the U.S. population, respectively, are disproportionately affected by the COVID-19 pandemic.


Thornton J. Covid-19: Africa’s case numbers are rising rapidly, WHO warns. BMJ 2020; 369. Full-text: https://doi.org/10.1136/bmj.m2394

A brief but concerning review on the situation in Africa. Since the virus was first detected in Egypt on 14 February, it took 98 days to reach 100,000 cases and only 18 days to move to 200,000 cases on the continent. More than 5,600 people have died from the illness, 70% of whom were in just five countries: Algeria, Egypt, Nigeria, South Africa, and Sudan.


17 June


Davies NG, Klepac P, Liu Y et al. Age-dependent effects in the transmission and control of COVID-19 epidemics. Nat Med 2020, June 16. https://doi.org/10.1038/s41591-020-0962-9 l (Important)

Do children have a lower susceptibility to infection? Probably yes. The authors used epidemic data from Canada, China, Italy, Japan, Singapore, and South Korea to determine the level of susceptibility and clinical symptoms in various age groups. Susceptibility to infection in individuals under 20 years of age was approximately half that of adults aged over 20 years, and clinical symptoms manifest in 21% (95% confidence interval: 12–31%) of infections in 10- to-19-year-olds, rising to 69% (57–82%) of infections in people aged over 70 years. These estimates have implications for the expected global burden of COVID-19, as a result of demographic differences across settings.


Kucharski AJ, Klepac P, Conlan AJ, et al. Effectiveness of isolation, testing, contact tracing, and physical distancing on reducing transmission of SARS-CoV-2 in different settings: a mathematical modelling study. The Lancet Infectious Diseases 2020 Published: June 16, 2020. Full-text: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30457-6/fulltext

Another mathematical modelling study, using pandemic data from 40,162 UK participants and simulating the effect of a range of different testing, isolation, tracing, and physical distancing scenarios. If combined with moderate physical distancing measures, self-isolation and contact tracing would be more likely to achieve control of SARS-CoV- 2 transmission.


18 June


Soriano V, Meiriño R, Corral O, Guallar MP. SARS-CoV-2 antibodies in adults in Madrid, Spain. Clin Infect Dis. 2020 Jun 16:ciaa769. PubMed: https://pubmed.gov/32544951. Full-text: https://doi.org/10.1093/cid/ciaa769

Madrid has been the most deeply hit region by COVID-19 in Spain, with 65,000 confirmed cases and 9,000 deaths up to May 10th, eight weeks after the country’s lockdown had been implemented on March 14th. The authors found that roughly 10.9% of adults in Madrid (excluding those living in communities of 10 to 25 persons) had SARS-CoV-2 antibodies at the time of lockdown release on May 10th.


19 June


Emeruwa UN, Ona S, Shaman JL, et al. Associations Between Built Environment, Neighborhood Socioeconomic Status, and SARS-CoV-2 Infection Among Pregnant Women in New York City. JAMA 2020, June 18, 2020. Full-text: https://doi.org/10.1001/jama.2020.11370

This cross-sectional study of 396 pregnant New York City residents delivering at New York hospitals showed that the likelihood of SARS-CoV-2 varied substantially across measures of built environment and neighborhood socioeconomic status. Large household membership, household crowding, and low socioeconomic status were associated with a 2-3 fold higher risk of infection.


Devi S. COVID-19 resurgence in Iran. Lancet 2020, June 20, 2020.  Full-text: https://doi.org/10.1016/S0140-6736(20)31407-0

Brief overview. Iran was one of the first countries to experience a COVID-19 epidemic, and began relaxing restrictions in April. Cases dropped, with fewer than 1000 new cases per day by the start of May, but daily cases have since increased, with the Iranian Health Ministry reporting 2,410 new cases on June 13.


Clapham H, Hay J, Routledge I, et al. Seroepidemiologic Study Designs for Determining SARS-COV-2 Transmission and Immunity. Emerg Infect Dis. 2020 Jun 16;26(9). PubMed: https://pubmed.gov/32544053. Full-text: https://doi.org/10.3201/eid2609.201840

Numerous challenges exist in terms of sample collection, what the presence of antibodies actually means, and appropriate analysis and interpretation to account for test accuracy and sampling biases. The authors review strengths and limitations of different assay types and study designs, and discuss methods for rapid sharing and analysis of serologic data.


20 June


Truelove S, Abrahim O, Altare C, et al. The potential impact of COVID-19 in refugee camps in Bangladesh and beyond:  A modeling study. PLoS Med 2020 Jun 16;17(6):e1003144. PubMed: https://pubmed.gov/32544156. Full-text: https://doi.org/10.1371/journal.pmed.1003144

Bangladesh hosts almost 1 million Rohingya refugees from Myanmar, with 600,000 concentrated in the Kutupalong-Balukhali Expansion Site. Using different transmission models and considering the age distribution in the camp, the authors expect 2,040-2,880 deaths (assuming that age was the primary determinant of infection severity and hospitalization). They also expect that comorbidities, limited hospitalization, and intensive care capacity may increase this risk.


21 June


Twahirwa Rwema JO, Diouf D, Phaswana-Mafuya N, et al. COVID-19 Across Africa: Epidemiologic Heterogeneity and Necessity of Contextually Relevant Transmission Models and Intervention Strategies. Ann Intern Med. 2020 Jun 18. PubMed: https://pubmed.gov/32551812. Full-text: https://doi.org/10.7326/M20-2628

Brief overview on the burden and outcomes associated with COVID-19 in Africa, showing substantial variations across countries. Some explanations why many multiple mathematical models have failed to project the epidemic on the continent.


Han X, Wei X, Alwalid O, et al. Severe Acute Respiratory Syndrome Coronavirus 2 among Asymptomatic Workers Screened for Work Resumption, China. Emerg Infect Dis. 2020 Jun 17;26(9). PubMed: https://pubmed.gov/32553070. Full-text: https://doi.org/10.3201/eid2609.201848

It’s not completely gone. After the outbreak in Wuhan, China, the authors assessed 29,299 workers screened with PCR during March 13–April 25, 2020. They noted 18 (0.06%) cases of asymptomatic infection; 13 turned negative within 8.0 days, and 41 close contacts tested negative. Of 22,633 persons tested for SARS-CoV-2 antibodies, 617 (2.7%) cases had positive IgG but negative IgM; 196 (0.87%) cases had positive IgG and IgM; and 40 (0.18%) cases had negative IgG but positive IgM.


Czeisler MÉ, Tynan MA, Howard ME, et al. Public Attitudes, Behaviors, and Beliefs Related to COVID-19, Stay-at-Home Orders, Nonessential Business Closures, and Public Health Guidance – United States, New York City, and Los Angeles, May 5-12, 2020. MMWR Morb Mortal Wkly Rep. 2020 Jun 19;69(24):751-758. PubMed: https://pubmed.gov/32555138. Full-text: https://doi.org/10.15585/mmwr.mm6924e1

Most people agree: during the week of May 5–12, 2020, a survey among 2,402 adults in New York City and Los Angeles and broadly across the United States found widespread support of stay-at-home orders and nonessential business closures and high degree of adherence to COVID-19 mitigation guidelines. 74-82% reported they would not feel safe if these restrictions were lifted nationwide at the time the survey was conducted. In addition, among those who reported that they would not feel safe, some indicated that they would nonetheless want community mitigation strategies lifted and would accept associated risks (13-17%, respectively).


22 June


Percivalle E, Cambiè G, Cassaniti I, et al. Prevalence of SARS-CoV-2 specific neutralising antibodies in blood donors from the Lodi Red Zone in Lombardy, Italy, as at 06 April 2020. Euro Surveill. 2020;25(24. Full-text: https://doi.org/10.2807/1560-7917.ES.2020.25.24.2001031

This study evaluated SARS-CoV-2 RNA and neutralizing antibodies in blood donors (BD) residing in the highly affected “Lodi Red Zone”, Italy (an area of 169 km2, including 10 municipalities and 51,500 inhabitants, which went into lockdown in February 2020). Of 390 BDs recruited after 20 February − when the first COVID-19 case in Lombardy was identified, 91 (23%) aged 19–70 years were antibody positive.


Savulescu J, Cameron J. Why lockdown of the elderly is not ageist and why levelling down equality is wrong. J Med Ethics. 2020 Jun 19:medethics-2020-106336. PubMed: https://pubmed.gov/32561661. Full-text: https://doi.org/10.1136/medethics-2020-106336

Some intelligent thoughts on a “partial” lockdown for the elderly. The authors think that ethically, selective isolation is permissible. It is not unjust discrimination. It is analogous to only screening women for breast cancer: selecting those at a higher probability of suffering from a disease. Even if it were unjust discrimination, it would be proportionate because it brings benefits to the elderly and is necessary given the grave risks to the economy and subsequent well-being of the larger population of an indiscriminate lockdown. To oppose selective isolation of the elderly is to engage in a levelling down of equality which is itself morally questionable. There is no Hollywood happy ending here where everyone is a winner. Everything has its upsides and its downsides.


24 June


Britton T, Ball F, Trapman P. A mathematical model reveals the influence of population heterogeneity on herd immunity to SARS-CoV-2. Science 23 Jun 2020. Full-text: https://doi.org/10.1126/science.abc6810

43%, not 60%: Disease-induced herd immunity may be achieved at a substantially lower percentage than the classical herd immunity level derived from mathematical models assuming homogeneous immunization. The model indicates a reduction of herd immunity from 60% under homogeneous immunization down to 43% (assuming R0 = 2.5) in a structured population, but this should be interpreted as an illustration, rather than an exact value or even a best estimate.


25 June


Lewis M, Sanchez R, Auerbach S, et al. COVID-19 Outbreak Among College Students After a Spring Break Trip to Mexico — Austin, Texas, March 26–April 5, 2020. MMWR Morb Mortal Wkly Rep. ePub: 24 June 2020. Full-text: http://dx.doi.org/10.15585/mmwr.mm6926e1

A college spring break trip mid-March led to 64 cases (14 asymptomatic and 50 symptomatic at the time of testing), including 60 among 183 vacation travelers, one among 13 household contacts, and three among 35 community contacts. Asymptomatic persons or those with mild symptoms likely played an important role in sustaining transmission. Prompt epidemiologic investigation contributed to outbreak control.


27 June


Horton R. Offline: The second wave. Lancet 2020, June 27, 395, ISSUE 10242, P1960. Full-text: https://doi.org/10.1016/S0140-6736(20)31451-3

Not in a good mood today? Then don’t read this important comment on what will likely happen during the next months. The first wave of the 1918 influenza pandemic took place between March and July. It proved relatively mild. The second wave arrived in August. It was much worse. Most of the 50–100 million deaths caused by influenza took place during 13 weeks between September and December, 1918. In many countries, the test, trace, and isolate system is still not fully functional and we have angry debates about whether physical distancing should be 1 m or 2 m. Scientists predict that a second wave will arrive in September, peaking by the end of 2020. Just sayin’.


29 June


Nagler AR, Goldberg ER, Aguero-Rosenfeld ME, et al. Early Results from SARS-CoV-2 PCR testing of Healthcare Workers at an Academic Medical Center in New York City. Clin Inf Dis, June 28, 2020. Full-text: https://doi.org/10.1093/cid/ciaa867

Widespread testing of HCW offers valuable information for hospital workflow and workforce amid an epidemic that threatened to overwhelm the healthcare system. Over eight weeks, 14,764 employees were tested: 33% of employees were symptomatic, 8% of asymptomatic employees reported COVID-19 exposure, 3% of employees returning to work were antibody-positive. Positivity rates declined over time.


Hong LX, Lin A, He ZB, et al. Mask wearing in pre-symptomatic patients prevents SARS-CoV-2 transmission: An epidemiological analysis. Travel Med Infect Dis. 2020 Jun 24;36:101803. PubMed: https://pubmed.gov/32592903. Full-text: https://doi.org/10.1016/j.tmaid.2020.101803

The incidence of COVID-19 doubled (19.0% vs. 8.1%) for local residents who had close contact with people returning from Wuhan, who did not wear masks and turned out to be pre-symptomatic COVID-19 patients. In this study, a cluster of 21 local COVID-19 patients originated from a couple returning from Wuhan who played cards sequentially in a space-limited Chess and Card Room or who were living together over a longer-term with pre-symptomatic or asymptomatic relatives. No bridge for grandma during these days.


30 June


Njuguna H, Wallace M, Simonson S, et al. Serial Laboratory Testing for SARS-CoV-2 Infection Among Incarcerated and Detained Persons in a Correctional and Detention Facility — Louisiana, April–May 2020. MMWR Morb Mortal Wkly Rep. ePub: 29 June 2020. Full-text: http://dx.doi.org/10.15585/mmwr.mm6926e2

High COVID-19 attack rates can occur in correctional and detention facilities. During May 7–21, among 98 incarcerated and detained persons in Louisiana who were quarantined because of virus exposure , 71 (72%) had lab-confirmed SARS-CoV-2 infection identified through serial testing, among them 45% without any symptoms at the time of testing. These findings suggest ongoing transmission among quarantined persons living in close settings; therefore, serial testing of contacts of persons with COVID-19 in correctional and detention facilities can identify asymptomatic and presymptomatic persons who would be missed through symptom screening alone.


Brown NE, Bryant-Genevier J, Bandy U, Browning CA, Berns AL, Dott M, et al. Antibody responses after classroom exposure to teacher with coronavirus disease, March 2020. Emerg Infect Dis. 2020 Sep [date cited]. https://doi.org/10.3201/eid2609.201802

No big surprise: classroom interaction between an infected teacher and students might result in virus transmission. After returning from Europe to the United States on March 1, 2020, a symptomatic teacher received positive test results. In total 2/21 students exposed to the teacher in the classroom had positive serologic results.


Pulla P. ‘The epidemic is growing very rapidly’: Indian government adviser fears coronavirus crisis will worsen. Nature 2020, June 26. Full-text: https://www.nature.com/articles/d41586-020-01865-w

Interview with Jayaprakash Muliyil, an epidemiologist and advisor of the Indian government, providing insight into the epidemic in India where the virus seems to spread much faster and the infection rates are higher. A discussion on why officials in some badly affected cities seem reluctant to say that outbreaks are being driven by community transmission — where cases cannot be linked to known sources.


1 July


Tenforde MW, Billig Rose E, Lindsell CJ, et al. Characteristics of Adult Outpatients and Inpatients with COVID-19 – 11 Academic Medical Centers, United States, March-May 2020. MMWR Morb Mortal Wkly Rep. 2020 Jul 3;69(26):841-846. PubMed: https://pubmed.gov/32614810. Full-text: https://doi.org/10.15585/mmwr.mm6926e3

Telephone interviews in a random sample of 350 adults aged ≥ 18 years who had positive RT-PCR in outpatient and inpatient settings at 11 U.S. academic medical centers in nine states revealed that only 46% were aware of recent close contact with someone with COVID-19, highlighting a need for increased screening, case investigation, contact tracing, and isolation of infected persons during periods of community transmission. Of note, approximately one third of symptomatic outpatients reported that they had not returned to baseline health by the interview date 14–21 days after testing positive.


3 July


Cheng SY, Wang J, Shen AC, et al. How to Safely Reopen Colleges and Universities During COVID-19: Experiences From Taiwan. Ann Int Med 2020, Jul 2. Full-text: https://doi.org/10.7326/M20-2927

Reopening colleges and universities poses a special challenge worldwide. Taiwan is one of the few countries where schools are functioning normally. To secure the safety of students and staff, the Ministry of Education in Taiwan established general guidelines, including a combination of strategies  such as – our future? – active campus-based screening and access control; school-based screening and quarantine protocols; student and faculty quarantine when warranted; mobilization of administrative and health center staff; regulation of dormitories and cafeterias; and reinforcement of personal hygiene, environmental sanitation, and indoor air ventilation practices. Somewhat depressing, but necessary?.


Callaghan AW, Chard AN, Arnold P, et al. Screening for SARS-CoV-2 Infection Within a Psychiatric Hospital and Considerations for Limiting Transmission Within Residential Psychiatric Facilities – Wyoming, 2020. MMWR Morb Mortal Wkly Rep. 2020 Jul 3;69(26):825-829. PubMed: https://pubmed.gov/32614815. Full-text: https://doi.org/10.15585/mmwr.mm6926a4

Following admission of two patients with SARS-CoV-2 infection on April 13, 2020, in the absence of specific guidance on prevention and management of COVID-19 in psychiatric facilities, the state hospital implemented expanded admission screening and infection prevention and control procedures. The results of the point prevalence survey, indicating no further transmission among patients and HCW almost 3 weeks after admission of the two SARS-CoV-2-positive patients, suggested that the expanded procedures might have been effective.


4 July


Yu X, Wei D, Chen Y, et al. Retrospective detection of SARS-CoV-2 in hospitalized patients with influenza-like illness. Emerging Microbes & Infections 2020, Full-text: https://doi.org/10.1080/22221751.2020.1785952

No cryptic transmission before early officially confirmed cases. In this retrospective screening for SARS-CoV-2 RNA in 1,271 nasopharyngeal swab samples, as well as the prevalence of IgM, IgG, and total antibodies against SARS-CoV-2 in 357 matched serum samples collected from hospitalized patients with influenza-like illness between December 1, 2018 and March 31, 2020 in Shanghai Ruijin Hospital, the onset date of the earliest COVID-19 case was January 25.


5 July


Petersen E, Koopmans M, Go U, et al. Comparing SARS-CoV-2 with SARS-CoV and influenza pandemics. Lancet Inf Dis 2020, July 03, 2020. Full-text: https://doi.org/10.1016/S1473-3099(20)30484-9

The basic reproductive rate (R0) for SARS-CoV-2 is estimated to be 2·5 (range 1·8–3·6) compared with 2·0–3·0 for SARS-CoV and the 1918 influenza pandemic, 0·9 for MERS-CoV, and 1·5 for the 2009 influenza pandemic. In their viewpoint, the authors postulate that historical evidence from prior influenza pandemics indicates that pandemics tend to come in waves over the first 2–5 years as population immunity builds-up (naturally or through vaccination) and that this is the most likely trajectory for SARS-CoV-2. A combination of physical distancing, enhanced testing, quarantine, and contact tracing will be needed for a long time.


6 July


Adam D. A guide to R — the pandemic’s misunderstood metric. Nature News. 03 July 2020. Full-text: https://www.nature.com/articles/d41586-020-02009-w

Nice article about what R, the reproduction number, can and can’t tell us about managing COVID-19. Politicians seem to have embraced R with enthusiasm but it’s far more important to watch for clusters of cases and to set up comprehensive systems to test people, trace their contacts and isolate those infected, than to look at R.


Pollán M,  Pérez-Gómez B,  Pastor-Barriuso  R, et al. Prevalence of SARS-CoV-2 in Spain (ENE-COVID): a nationwide, population-based seroepidemiological study. The Lancet 2020, July 06, 2020. Full-text: https://doi.org/10.1016/S0140-6736(20)31483-5

The vast majority (95%) of the Spanish population is seronegative, even in hotspot areas. In this nationwide, representative study, 61,075 participants were tested. Seroprevalence was 5·0% (95% CI 4.7–5.4) by the point-of-care test and 4.6% (4.3–5.0) by immunoassay, with a lower seroprevalence in children younger than 10 years (< 3.1% by the point-of-care test). There was high geographical variability, with higher prevalence around Madrid (> 10%) and lower in coastal areas (< 3%).


Eckerle I, Meyer B. SARS-CoV-2 seroprevalence in COVID-19 hotspots. The Lancet July 06, 2020. Full-text: https://doi.org/10.1016/S0140-6736(20)31482-3

Comment on these findings. Most of the population appears to have remained unexposed to SARS-CoV-2, even in areas with widespread virus circulation. Any proposed approach to achieve herd immunity through natural infection is not only highly unethical, but also unachievable. With a large majority of the population being infection-naïve, virus circulation can quickly return to early pandemic dimensions in a second wave once measures are lifted.


8 July


Kang CR, Lee JY, Park Y, Huh IS, Ham HJ, Han JK, et al. Coronavirus disease exposure and spread from nightclubs, South Korea. Emerg Infect Dis. 2020 Sep. Full-text: https://doi.org/10.3201/eid2610.202573 l (Important)

Despite low incidence, superspreading related to visiting nightclubs has the potential to spark a resurgence of cases. This article describes large-scale testing for active case-finding among persons who visited 5 Itaewon nightclubs in downtown Seoul, South Korea. Nightclubs had reopened ahead of the April 30–May 5 Golden Week holiday. Among the 41,612 total tests (!) conducted by May 25, positive results were found in 0.19% (67/35,827) of nightclub visitors, 0.88% (51/5,785) of their contacts, and 0.06% (1/1,627) of anonymously tested persons. 246 COVID-19 cases were associated with the reopening of nightclubs in Seoul. Hooray for the Asian thoroughness and some strong arguments against reopening nightclubs…


Yehya N, Venkataramani A, Harhay MO. Statewide Interventions and Covid-19 Mortality in the United States: An Observational Study. Clin Infect Dis. 2020 Jul 8. PubMed: https://pubmed.gov/32634828. Full-text: https://doi.org/10.1093/cid/ciaa923

Every day counts. In this large, nationwide study, later statewide emergency declarations and school closures were associated with higher COVID-19 mortality. Each day of delay increased mortality risk by 5 to 6%.


Waltenburg MA, Victoroff T, Rose CE, et al. Update: COVID-19 Among Workers in Meat and Poultry Processing Facilities – United States, April–May 2020. MMWR Morb Mortal Wkly Rep. ePub: 7 July 2020. Full-text: https://www.cdc.gov/mmwr/volumes/69/wr/mm6927e2.htm

One more reason to go veg. Overall, 239 facilities reported 16,233 COVID-19 cases and 86 COVID-19–related deaths among workers. The percentage of workers with COVID-19 ranged from 3.1% to 24.5% per facility. Among seven facilities that implemented facility-wide testing, the crude prevalence of asymptomatic or presymptomatic infections among 5,572 workers who had positive SARS-CoV-2 test results was 14.4%.


9 July


Saloner B, Parish K, Ward JA. COVID-19 Cases and Deaths in Federal and State Prisons. JAMA July 8, 2020. Full-text: https://doi.org/10.1001/jama.2020.12528

By June 6, 2020, there had been 42,107 cases of COVID-19 and 510 deaths among 1.3 million prisoners in the US. The case rate was initially lower in prisons but surpassed the US population on April 14, 2020. The mean daily case growth rate was 8.3% per day in prisons and 3.4% per day in the US population.


Maxmen A. California’s San Quentin prison declined free coronavirus tests and urgent advice — now it has a massive outbreak. Nature NEWS 07 July 2020. Full-text: https://doi.org/10.1038/d41586-020-02042-9

And this is a story behind the numbers. San Quentin Prison, which got through most of May without a single reported case among inmates, is now dealing with the third-largest coronavirus outbreak in the US. More than one-third of the inmates and staff (1,600 people) have tested positive. Six have died. Researchers fear that other institutions are at risk.


10 July


Houlihan CF, Vora N, Byrne T, et al. Pandemic peak SARS-CoV-2 infection and seroconversion rates in London frontline health-care workers. Lancet July 09, 2020. Full-text: https://doi.org/10.1016/S0140-6736(20)31484-7

A total of 200 high-risk frontline HCWs were enrolled between March 26 and April 8 in a prospective cohort study in an acute National Health Service hospital trust in London. 25% of HCWs were already seropositive at enrolment and a further 20% became seropositive within the first month of follow-up. Most infections occurred between March 30 and April 5, the week with the highest number of new cases in London.


The Lancet. COVID-19: the worst may be yet to come. Lancet July 11, 2020. Full-text: https://doi.org/10.1016/S0140-6736(20)31517-8

What a depressing editorial. Don’t read this if you’re in a bad mood. Five months after WHO declared the SARS-CoV-2 outbreak a global health emergency, the virus continues to beat a concerning and complex path. For much of the globe, the worst may be yet to come.


Watsa M. Rigorous wildlife disease surveillance. Science 10 Jul 2020, 369: 145-147. Full-text: https://doi.org/10.1126/science.abc0017

There are no international or national conventions on pathogen screening associated with animals, animal products or their movements. Capacity for emerging infectious disease (EID) diagnostics is limited along much of the human-wildlife interface. EID risks associated with the wildlife trade remain the largest unmet challenge of current disease surveillance efforts. According to this comment, an internationally recognized standard for managing wildlife trade on the basis of known disease risks should be established.


11 July


Torres JP, Piñera C, De La Maza V, et al. SARS-CoV-2 antibody prevalence in blood in a large school community subject to a Covid-19 outbreak: a cross-sectional study. Clin Infect Dis. 2020 Jul 10:ciaa955. PubMed: https://pubmed.gov/32649743. Full-text: https://doi.org/10.1093/cid/ciaa955

In this school-based outbreak in Santiago, Chile identified on March 12, affecting nearly 50 people among school and household members, antibody positivity rates based on a self-administered test were 9.9% for 1,009 students and 16.6% for 235 staff. Among students, positivity was associated with younger age (p = 0.01), lower grade level (p = 0.05), prior RT-PCR positivity (p = 0.03), and history of contact with a confirmed case (p < 0.001). Among staff, positivity was higher in teachers (p = 0.01) and in those previously RT-PCR positive (p < 0.001). Teachers were more affected during the outbreak and younger children were at higher infection risk, likely because index case(s) were teachers and/or parents from preschool. Reopening schools should focus on avoiding new cases among teachers.


12 July


Verdery AM, Smith-Greenaway E, Margolis R, Daw J. Tracking the reach of COVID-19 kin loss with a bereavement multiplier applied to the United States. Proc Natl Acad Sci U S A. 2020 Jul 10:202007476. PubMed: https://pubmed.gov/32651279. Full-text: https://doi.org/10.1073/pnas.2007476117

Multiply deaths by nine. These authors created a “bereavement multiplier”, an indicator that clarifies the downstream impact of COVID-19 mortality and can be applied to different epidemiological projections of death counts: how many people are at risk for losing a grandparent, parent, sibling, spouse, or child for each COVID-19 death. In the US, every death from COVID-19 will leave approximately nine bereaved.


Fenton MB. Bats navigate with cognitive maps. Science 10 Jul 2020: Vol. 369, Issue 6500, pp. 142. Full-text: https://doi.org/10.1126/science.abd1213

Interested in bats these days? They are smart. And they know where they are. This article summarizes current research on the path-finding strategies of fruit bats. Bats do not systematically follow known routes, nor do they directly sense cues such as landmarks or beacons: they rely on a cognitive map frame of reference for their current positions in relation to a goal that they had not yet detected.


14 July


Rincón  A, Moreso F, López-Herradón A. The keys to control a coronavirus disease 2019 outbreak in a haemodialysis unit.  Clinical Kidney Journal, 13 July 2020. Full-text:  https://doi.org/10.1093/ckj/sfaa119

Outbreak in an hemodialysis unit in Barcelona, involving 18% of patients receiving treatment in this facility. In total, 22 symptomatic and 14 of the 170 asymptomatic patients became infected. The main risk factors for SARS-CoV-2 infection were sharing health-care transportation, living in a nursing home and having been admitted to the reference hospital within the previous 2 weeks.


16 July


Islam N, Sharp SJ, Chowell G, et al. Physical distancing interventions and incidence of coronavirus disease 2019: natural experiment in 149 countries. BMJ. 2020 Jul 15;370:m2743. PubMed: https://pubmed.gov/32669358. Full-text: https://doi.org/10.1136/bmj.m2743

Be fast – but don’t close the metro. In this large empirical study, data from 149 countries were pooled, in order to estimate the relative effectiveness of different policy interventions within each country. Implementation of any physical distancing intervention was associated with an overall incidence reduction of 13% (IRR 0.87). Closure of public transport was not associated with any additional reduction when the other four physical distancing interventions were in place. Data from 11 countries also suggested similar overall effectiveness (IRR 0.85) when school closures, workplace closures, and restrictions on mass gatherings were in place. Earlier implementation of lockdown was associated with a larger reduction (IRR 0.86) compared with a delayed implementation of lockdown after other physical distancing interventions were in place (IRR 0.90).


20 July


Ruktanonchai NW, Floyd JR, Lai S, et al. Assessing the impact of coordinated COVID-19 exit strategies across Europe. Science. 2020 Jul 17:eabc5096. PubMed: https://pubmed.gov/32680881. Full-text: https://doi.org/10.1126/science.abc5096

Collaboration is better than unilateralism (some people should have thought about that before voting pro-Brexit). Using mobile phone and case data to quantify how coordinated exit strategies can delay European resurgence of COVID-19, the authors conclude that synchronizing intermittent lockdowns would reduce the number of total lockdown periods. It doesn’t escape their notice that the implications of their study extend well beyond Europe and COVID-19.


22 July


Ali ST, Wang L, Lau EHY, et al. Serial interval of SARS-CoV-2 was shortened over time by nonpharmaceutical interventions. Science  21 Jul 2020. Full-text: https://doi.org/10.1126/science.abc9004

The serial interval is the time between illness onset in successive cases in a transmission chain. The authors show that during the early epidemic in China, the mean serial intervals of SARS-CoV-2 infection shortened from 7.8 days to 2.6 days between January 9 and February 13. This reduction was driven by intensive non-pharmaceutical interventions, particularly, reduction of the isolation delay period. Isolation of an infector one day earlier is expected to reduce the mean serial interval by 0.7 days.


23 July


Sudharsanan N, Didzun O, Bärnighausen T Geldsetzer P. The Contribution of the Age Distribution of Cases to COVID-19 Case Fatality Across Countries – A 9-Country Demographic Study. Ann Intern Med 2020, published 22 July. Full-text: https://doi.org/10.7326/M20-2973

The overall observed case-fatality rates (CFR) vary widely, with the highest rates in Italy (9.3%) and the Netherlands (7.4%) and the lowest rates in South Korea (1.6%) and Germany (0.7%). This cross-sectional study of population-based data from China, France, Germany, Italy, the Netherlands, South Korea, Spain, Switzerland, and the US finds that age distribution of cases explains 66% of the variation of across countries, with a resulting age-standardized median CFR of 1.9%. See also the editorial by David N. Fisman, Amy L. Greer, and Ashleigh R. Tuite: Age Is Just a Number: A Critically Important Number for COVID-19 Case Fatality; full-text: https://doi.org/10.7326/M20-4048.


Fisman DN, Bogoch I, Lapointe-Shaw L, et al. Risk Factors Associated With Mortality Among Residents With Coronavirus Disease 2019 (COVID-19) in Long-term Care Facilities in Ontario, Canada.  JAMA, published July 22, Full-text: https://doi.org/10.1001/jamanetworkopen.2020.15957

The authors compare the risk of death from coronavirus disease 2019 (COVID-19) among residents of long-term care (LTC) homes with that among the general population in long-term care facilities in Ontario, Canada. In the LTC facility setting, the incidence of mortality was more than 13 times greater than that seen in community-living adults older than 69 years during a similar period. Infection among LTC staff was associated with death among residents with a 6-day lag.


24 July


Candido DS, Claro M, de Jesus JG, et al. Evolution and epidemic spread of SARS-CoV-2 in Brazil. Science 23 Jul 2020:eabd2161. Full-text: https://doi.org/10.1126/science.abd2161

Using a mobility-driven transmission model, the authors show that non-pharmaceutical interventions (lockdowns, etc) reduced the reproduction number from > 3 to 1 – 1.6 in São Paulo and Rio de Janeiro. In addition, after sequencing hundreds of genomes, they identified > 100 international virus introductions in Brazil with 76% of Brazilian strains falling into three clades that were introduced from Europe between 22 February and 11 March 2020. Finally, the study provides evidence that the current interventions (in an insalubrious political environment – note of the CR editor) remain insufficient to keep virus transmission under control in Brazil.


Havers FP, Reed C, Lim T, et al. Seroprevalence of Antibodies to SARS-CoV-2 in 10 Sites in the United States, March 23-May 12, 2020. JAMA Intern Med. 2020 Jul 21. PubMed: https://pubmed.gov/32692365. Full-text: https://doi.org/10.1001/jamainternmed.2020.4130

This cross-sectional study reports the presence of antibodies to SARS-CoV-2 spike protein in samples collected from March 23 through May 12, 2020, in 12 US sites from San Francisco to New York City. Adjusted estimates of the proportion of seropositive persons ranged from 1.0% in the San Francisco Bay area (collected April 23-27) to 6.9% of persons in New York City (collected March 23-April 1). The estimated number of SARS-CoV-2 infections is around 10 times the number of reported cases.


25 July


Liang, L., Tseng, C., Ho, H.J. et al. Covid-19 mortality is negatively associated with test number and government effectiveness. Sci Rep 10, 12567 (2020). Full-text: https://doi.org/10.1038/s41598-020-68862-x

In this worldwide cross-sectional study, the authors find that COVID-19 mortality is

  • Negatively associated with
    • Test number per 100 people
    • Government effectiveness score
    • Number of hospital beds
  • Positively associated with
    • Proportion of population aged 65 or older
    • Transport infrastructure quality score

Remember: Government effectiveness!


27 July


Jingwen Li, Chengbi Wu, Xing Zhang, Lan Chen, Xinyi Wang, Xiuli Guan, Jinghong Li, Zhicheng Lin, Nian Xiong. Post-pandemic testing of SARS-CoV-2 in Huanan Seafood Market area in Wuhan, China. Clinical Infectious Diseases 2020, published 25 July 2020. Full-text: https://doi.org/10.1093/cid/ciaa1043

The Wuhan lockdown lasted 76 days, from 23 January to 8 April, 2020. Two and a half weeks later, the number of both hospitalized COVID-19 patients and daily new cases in Wuhan decreased to zero. When sporadic cases were reported after May 11th, the Chinese authorities started a citywide mass nucleic acid testing of SARS-CoV-2 for all citizens in Wuhan city (14 May to 1 June 2020). Now Nian Xiong and colleagues report the results from 107,662 residents around the Huanan Seafood Market. Six (6) persons tested positive for SARS-CoV-2, accounting for 0.006%, the equivalent of 60 cases per million.


28 July


Vahidy FS, Bernard DW, Boom ML, et al. Prevalence of SARS-CoV-2 Infection Among Asymptomatic Health Care Workers in the Greater Houston, Texas, Area. JAMA Netw Open 2020;3(7):e2016451. Full-text: https://doi.org/10.1001/jamanetworkopen.2020.16451


29 July


McNeil Jr DG. A Viral Epidemic Splintering Into Deadly Pieces. The New York Times, 29 July 2020. Full-text: https://www.nytimes.com/2020/07/29/health/coronavirus-future-america.html

This is not a scientific paper, but it is better than two thirds of published and pre-published articles about COVID-19 epidemiology. More than 4,000 words thoughtfully put down by Donald G. McNeil Jr. If you don’t read it now, read it on the weekend.


30 July


Dawood FS, Ricks P, Njie GJ, et al. Observations of the global epidemiology of COVID-19 from the prepandemic period using web-based surveillance: a cross-sectional analysis. Lancet Infect Dis 2020, published 29 July. Full-text: https://doi.org/10.1016/S1473-3099(20)30581-8

Fatimah Dawood and colleagues describe the global spread of SARS-CoV-2 and characteristics of COVID-19 cases and clusters before WHO declared COVID-19 as a pandemic on 11 March 2020 (i.e., pre-pandemic). They identified cases of COVID-19 from official websites, press releases, press conference transcripts, and social media feeds of national ministries of health or other government agencies. Cases with travel links to China, Italy, or Iran accounted for almost two-thirds of the first reported COVID-19 cases from affected countries. There were many clusters of household transmission among early cases; however, clusters in occupational or community settings tended to be larger. This is good news for future pandemic waves. Keep your distance and slow the spread of SARS-CoV-2.


1 August

Today, revise what you have read and learned over the past months. A summary of articles about Immunology and Vaccines from the beginning:


2 August


Nguyen LH, Drew DA, Graham MS, et al. Risk of COVID-19 among front-line health-care workers and the general community: a prospective cohort study. Lancet Public Health 2020, published 31 July. Full-text: https://doi.org/10.1016/S2468-2667(20)30164-X

Front-line health care workers are at increased risk of SARS-CoV-2 infection. In a prospective, observational cohort study in the UK and the USA of the general community, including front-line health care workers, Andrew Chan and colleagues found that compared with the general community, front-line health care workers were at increased risk for reporting a positive COVID-19 test (adjusted HR 11·61, 95% CI 10·93–12·33). An increased risk (adjusted HR 3·40, 95% CI 3·37–3·43) was even found after accounting for differences in testing frequency between front-line health care workers and the general community. Post-hoc analyses showed that Black, Asian, and minority ethnic health care workers are at especially high risk of SARS-CoV-2 infection, with at least a fivefold (!) increased risk of COVID-19 compared with the non-Hispanic white general community.


de Souza WM, Buss LF, Candido DDS, et al. Epidemiological and clinical characteristics of the COVID-19 epidemic in Brazil. Nat Hum Behav. 2020 Jul 31. PubMed: https://pubmed.gov/32737472. Full-text: https://doi.org/10.1038/s41562-020-0928-4

Nuno Rodrigues Faria, Julio Croda and colleagues contextualize epidemiological, demographic and clinical findings for Brazilian COVID-19 cases in March, April and May 2020. By 31 May 2020, 514,200 COVID-19 cases and almost 30,000 deaths had been reported. They estimated a somewhat higher median transmission potential (R0) of SARS-CoV-2 of 3.1 (2.4–5.5) in Brazil compared with Italy, the United Kingdom, France, and Spain. As expected, more populated and better-connected municipalities were affected earlier, and less populated municipalities at a later stage of the epidemic.


3 August


Pham QT, Rabaa MA, Duong HL, et al. The first 100 days of SARS-CoV-2 control in Vietnam. Clin Infect Dis 2020, published 1 August. Full-text: https://doi.org/10.1093/cid/ciaa1130

One hundred days after the first SARS-CoV-2 case was reported in Vietnam on January 23rd, 270 cases were confirmed, with no deaths. Duc Anh Dang and colleagues describe the national control measures and conclude that Vietnam controlled SARS-CoV-2 spread through the early introduction of mass communication, meticulous contact-tracing with strict quarantine, and international travel restrictions. The value of these interventions is supported by the high proportion of asymptomatic and imported cases, and evidence for substantial pre-symptomatic transmission. A lesson for the world.


4 August


Kolthur-Seetharam U, Shah D, Shastri J, Juneja S, Kang G, Malani A, Mohanan M, Lobo GN, Velhal G, Gomare M. SARS-CoV2 Serological Survey in Mumbai by NITI-BMC-TIFR.  Tata Institute of Fundamental Research (TIFR) 2020, published 29 June. Full-text: https://www.tifr.res.in/TSN/article/Mumbai-Serosurvey%20Technical%20report-NITI.pdf

We usually prefer peer-reviewed studies and seldom present pre-published papers. We are even less readily inclined to present a PDF with just the technical details of an unpublished study. Today we make an exception. In a cross-sectional survey in Mumbai, India, Ullas Kolthur-Seetharam and colleagues estimated the prevalence of SARS-CoV-2 infection in three areas in Mumbai (called ‘wards’) in July 2020. The authors found, on average, a prevalence of around 57% in the slum areas of Chembur, Matunga and Dahisar, and 16% in neighboring non-slums. If these data are confirmed, some Mumbai areas would soon reach herd immunity and could return to a pre-COVID way of life. For many countries in the world, this would be the best piece of news since the beginning of the pandemic.


5 August


Sabbadini LL, Romano MC, et al. [First results of the seroprevalence survey  about SARS-CoV-2] (Primi risultati  dell’indagine di sieroprevalenza  sul SARS-CoV-2). Italian Health Ministery and National Statistics Institute 2020, published 3 August. Full-text (Italian): https://www.istat.it/it/files//2020/08/ReportPrimiRisultatiIndagineSiero.pdf

According to a representative study by the Italian Ministry of Health (64,000 participants), 1.5 million people (2.5% of the population) had SARS-CoV-2 antibodies during the study period from May 25 to July 15. This figure is higher than the currently reported 250,000 cases, but far less than an estimate by the UK Imperial College which projected the number of infected people in Italy to be 6 million on 28 March (95% credible interval: 1,932,800 – 15,704,000; see the full-text, published on 30 March). Perhaps to beware of Imperial College projections. The more important message of the Italian study: if these figures are true, the infection fatality rate (IFR, the proportion of deaths among all the infected individuals) in Italy would be 2.3% (35,000 deaths/1,500,000 infections). This is higher than in other European countries and needs to be addressed in future studies.


Panovska-Griffiths J, Kerr CC, Stuart RM, et al. Determining the optimal strategy for reopening schools, the impact of test and trace interventions, and the risk of occurrence of a second COVID-19 epidemic wave in the UK: a modelling study. Lancet Child Adolesc Health 2020, August 03, 2020. Full-text: https://doi.org/10.1016/S2352-4642(20)30250-9

Does anyone doubt this? To prevent a second wave, relaxation of physical distancing, including reopening of schools, must be accompanied by large-scale, population-wide testing of symptomatic individuals and effective tracing of their contacts, followed by isolation of diagnosed individuals. The authors estimate for the UK that without these levels of testing and contact tracing, reopening of schools together with gradual relaxing of the lockdown measures are likely to induce a second wave that would peak in December 2020 (if schools open full-time in September), having 2.0 – 2.3 times the size of the original COVID-19 wave.


7 August


To KK, Chan WM, Ip JD, et al. Unique SARS-CoV-2 clusters causing a large COVID-19 outbreak in Hong Kong. Clin Infect Dis. 2020 Aug 5:ciaa1119. PubMed: https://pubmed.gov/32756996. Full-text: https://doi.org/10.1093/cid/ciaa1119

With a total of 617 locally acquired laboratory-confirmed cases reported between July 5 and 21, Hong Kong has experienced the largest local COVID-19 outbreak since the beginning of the pandemic. This phylogenetic study by Kwok-Yung Yuen, Kelvin Kai-Wang To and colleagues shows that this outbreak was related to imported cases and not to silent carriers from previous waves. Two unique SARS-CoV-2 clusters were identified.


9 August


Baker MG, Anglemyer A. Successful Elimination of Covid-19 Transmission in New Zealand. N Engl J Med 2020, published 7 August. Full-text: https://www.nejm.org/doi/full/10.1056/NEJMc2025203

In mid-March, informed by science-based advocacy, national New Zealand leaders switched from a mitigation strategy to an elimination strategy. The government implemented a stringent countrywide lockdown which lasted 7 weeks (26 March – mid-May). Now, New Zealand views itself in the post-elimination stage, and public life has returned to near normal. The only cases identified are among international travelers who are kept in government-managed quarantine or isolation for 14 days after arrival. Michael Baker and Andrew Anglemyer conclude that rapid, science-based risk assessment linked to early, decisive government action was critical. The geographical isolation of New Zealand was another trump card the country had up its sleeve.


Heywood AE, Macintyre CR. Elimination of COVID-19: what would it look like and is it possible? Lancet 2020, published 6 August. Full-text: https://doi.org/10.1016/S1473-3099(20)30633-2

Anita Haywood and Raina Macintyre remember that the elimination of any infectious disease is ambitious, requiring substantial resources. They suggest a zero-case scenario of not less than three months before declaring an area SARS-CoV-2-free. For obvious reasons, islands or island states have the best chances to achieve this goal.


Moscola J, Sembajwe G, Jarrett M, et al. Prevalence of SARS-CoV-2 Antibodies in Health Care Personnel in the New York City Area. JAMA 2020, published 6 August. https://doi.org/10.1001/jama.2020.14765

Health care personnel (HCP) working in New York City had a high exposure risk for SARS-CoV-2 infection. To address this concern, the Northwell Health System, the largest in New York State, offered voluntary antibody testing to all HCPs. Now Karina Davidson and colleagues report the prevalence of SARS-CoV-2 among HCPs and associations with demographics, primary work location and type, and suspicion of viral exposure. They found a 13.7% prevalence of SARS-CoV-2 antibodies (5523 of 40,329 HCWs tested) which was similar to that among adults randomly tested in New York State (14.0%).


Petersen MS, Strøm M, Christiansen DH, Fjallsbak JP, Eliasen EH, Johansen M, et al. Seroprevalence of SARS-CoV-2–specific antibodies, Faroe Islands. Emerg Infect Dis 2020 Nov. Published August 2020. Full-text: https://doi.org/10.3201/eid2611.202736

Maria Petersen and colleagues conducted a nationwide study of the prevalence of SARS-CoV-2 infection in the Faroe Islands, an autonomous territory within the Kingdom of Denmark with a population of around 50,000. Of 1,075 randomly selected participants, 6 (0.6%) tested seropositive for antibodies to the virus. At present, small islands tend to have low seropositivity rates.


10 August


Kalk A, Schultz A. SARS-CoV-2 epidemic in African countries—are we losing perspective? Lancet, August 07, 2020. Full-text: https://doi.org/10.1016/S1473-3099(20)30563-6

Important comment on modelling studies predicting a huge death toll for some African countries. In the Democratic Republic of the Congo and Malawi, for instance, only 2-3% of the population is older than 65 years. According to the two authors (who work in these countries), the lockdown measures proposed by others do not appear applicable to the African continent and might cause more harm than SARS-CoV-2 itself.


13 August


Steinberg J, Kennedy ED, Basler C, et al. COVID-19 Outbreak Among Employees at a Meat Processing Facility — South Dakota, March–April 2020. MMWR Morb Mortal Wkly Rep 2020;69:1015–1019. Full-text: http://dx.doi.org/10.15585/mmwr.mm6931a2

Detailed report of an outbreak in a meat processing facility in South Dakota. From March 16 to April 25, 25.6% (929) of employees and 8.7% (210) of their contacts were diagnosed with COVID-19; two employees died. The highest attack rates occurred among employees who worked < 6 feet (2 meters) from one another on the production line.


14 August


Ward H, Atchison C, Whitaker M, et al. Antibody prevalence for SARS-CoV-2 following the peak of the pandemic in England: REACT2 study in 100,000 adults. Imperial College London 2020. Pre-print: https://www.imperial.ac.uk/media/imperial-college/institute-of-global-health-innovation/Ward-et-al-120820.pdf

By the end of June, an estimated 3.4 million people, or slightly under 6% of the UK population, had antibodies to the virus and had likely had COVID-19. London had the highest numbers (13%), while the South West had the lowest (3%). This is the result of the REACT (REal Time Assessment of Community Transmission) study, by Helen Ward, Paul Elliott and colleagues from the Imperial College London, using antibody finger-prick self-testing at home to track past infections. Black, Asian and minority ethnic (BAME) individuals were between two and three times as likely to have had SARS-CoV-2 infection compared to white people. An interesting trend: young people aged 18-24 had the highest rates (8%), while older adults aged 65 to 74 were least likely to have been infected (3%).


16 August


Sebhatu A, Wennberg K, Arora-Jonsson S, et al. Explaining the homogeneous diffusion of COVID-19 nonpharmaceutical interventions across heterogeneous countries. PNAS August 11, 2020. Full-text:  https://doi.org/10.1073/pnas.2010625117

What drives OECD countries to adopt COVID-19 restrictive policies such as lockdowns and school closures? These Swedish researchers found that government policies are strongly driven by the policies initiated in other countries. The level of democracy also matters: While strong democracies are slower to initiate restrictive policies, they are more likely to follow the policies of nearby countries. Following the lead of others rather than making decisions based on the specific situation of the country may have led to countries locking down too early or too late.


20 August


Rivera F, Safdar N, Ledeboer N, et al. Prevalence of SARS-CoV-2 asymptomatic infections in two large academic health systems in Wisconsin. Clinical Infectious Diseases 19 August 2020. Full-text: https://doi.org/10.1093/cid/ciaa1225

From April 6 2020 to June 4 2020, a total of 11,654 asymptomatic patients were tested for SARS-CoV-2 in two large academic health systems in two counties of Wisconsin. Since early April 2020, both health systems implemented SARS-CoV-2 testing on all hospitalizations, on all patients scheduled for elective surgeries, including deliveries, or among all patients with known SARS-CoV-2 exposure in the absence of symptoms. In total, only 61 (0.52%) were positive. In both of these counties, rates were low, despite the higher incidence of COVID-19 in Milwaukee county.


22 August


Hatcher SM, Agnew-Brune C, Anderson M, et al. COVID-19 Among American Indian and Alaska Native Persons — 23 States, January 31–July 3, 2020. MMWR Morb Mortal Wkly Rep 2020, published 19 August 2020. Full-text: http://dx.doi.org/10.15585/mmwr.mm6934e1

American Indian and Alaska Native (AI/AN) persons appear to be disproportionately affected by the COVID-19 pandemic. Now Sarah Hatcher et al. report that the overall COVID-19 incidence among AI/AN persons was 3.5 times that among white persons (594 per 100,000 AI/AN population compared with 169 per 100,000 white population). The authors discuss the factors which most likely contributed to the observed elevated incidence.


Jiménez MC, Cowger TL, Simon LE, Behn M, Cassarino N, Bassett MT. Epidemiology of COVID-19 Among Incarcerated Individuals and Staff in Massachusetts Jails and Prisons. JAMA Netw Open 2020;3(8). Full-text: https://doi.org/10.1001/jamanetworkopen.2020.18851

Of 14,987 individuals incarcerated across Massachusetts prison facilities, 1032 confirmed cases of COVID-19 were reported among incarcerated individuals (n = 664) and staff (n = 368) as of July 8, 2020. The rate of COVID-19 among incarcerated individuals was nearly 3 times that of the Massachusetts general population and 5 times the US rate. Monik Jiménez et al. stress that access to testing without coercion, de-carceration, and contact tracing are necessary to decrease harm from COVID-19 to incarcerated people and their communities.


26 August


Perkins TA, Cavany SM, Moore SM, et al. Estimating unobserved SARS-CoV-2 infections in the United States. PNAS August 21, 2020. Full-text:  https://doi.org/10.1073/pnas.2005476117

The authors quantified unobserved infections in the United States during the early weeks of the epidemic. After a national emergency was declared, fewer than 10% of locally acquired, symptomatic infections in the US may were detected over a period of a month. This gap in surveillance during a critical phase of the epidemic resulted in a large, unobserved reservoir by early March. Testing was a major limiting factor in assessing the extent of SARS-CoV-2 transmission during its initial invasion into the US.


27 August


Maxmen A. Why the United States is having a coronavirus data crisis. Nature 2020, published 25 August. Full-text: https://www.nature.com/articles/d41586-020-02478-z

Is the United States emerging as a Second-World country from the SARS-CoV-2 pandemic? The country suffers from a dearth of data, writes Amy Maxmen in this Nature news article. Reliable information on who is infected, why and where is simply missing. How could this happen?


31 August


Westhaus S, Weber FA, Schiwy S, et al. Detection of SARS-CoV-2 in raw and treated wastewater in Germany – Suitability for COVID-19 surveillance and potential transmission risks. Sci Total Environ 2020 August 18;751:141750. PubMed: https://pubmed.gov/32861187. Full-text: https://doi.org/10.1016/j.scitotenv.2020.141750

Detailed Analysis of a set of samples from nine wastewater treatment plants in North Rhine-Westphalia, Germany. Main conclusions: Yes, SARS-CoV-2 can be detected in wastewater in Germany using RT-qPCR. The total load of gene equivalents in wastewater correlated with the cumulative and the acute number of COVID-19 cases reported in the respective catchment areas. Thus, wastewater-based epidemiology can be regarded as a complementary measure to survey the outbreak. Note – negative tests for replication potential indicate that wastewater might be no major route for transmission to humans.


Graham NSN, Junghans C, McLaren R, et al. High rates of SARS-CoV-2 seropositivity in nursing home residents. J Infection August 26, 2020. Full-text: https://doi.org/10.1016/j.jinf.2020.08.040

What incredibly high infection rates in nursing homes! During March – April 2020 the authors investigated outbreaks in four UK nursing homes where 40% of 394 residents tested positive on RT-PCR. Now they demonstrate that COVID-19 infection was considerably more widespread. Seventy-two percent of nursing home residents (95% CI 66 – 77) were anti-SARS-CoV-2 IgG antibody positive, representing 173 of 241 residents available and consenting to testing. This included 93% of those tested who were previously RT-PCR positive and 59% of those who were previously RT-PCR negative. Seropositivity was not associated with the presence of comorbidities.


Fouillet A, Pontais I, Caserio-Schönemann C. Excess all-cause mortality during the first wave of the COVID-19 epidemic in France, March to May 2020. Eurosurveillance 2020;25(34. Full-text:  https://doi.org/10.2807/1560-7917.ES.2020.25.34.2001485

Through a weekly all-cause mortality surveillance system in France, the authors observed a major all-cause excess mortality from March to May 2020 (25,030 deaths, mainly among elderly people). Five metropolitan regions were the most affected, particularly the Île-de-France and the Grand-Est regions. However, assessing the excess mortality related to COVID-19 is complex because of the potential protective effect of the lockdown period on other causes of mortality.


1 September


Seemann T, Lance CR, Sherry NL, et al. Tracking the COVID-19 pandemic in Australia using genomics. Nat Commun 11, 4376 (2020). Full-text: https://doi.org/10.1038/s41467-020-18314-x

Genomic sequencing for rapid identification of SARS-CoV-2 transmission chains? That’s what Benjamin P. Howden and Torsten Seemann did in Victoria, Australia (1,333 COVID-19 cases). They combined extensive whole-genome sequencing and epidemiologic data to investigate the source of individual cases and identify distinct genomic clusters, including large clusters associated with social venues, healthcare visits and cruise ships. The authors demonstrate the critical role of multiple SARS-CoV-2 importations by returned international travelers in driving transmission in Australia, with travel-related cases responsible for establishing ongoing transmission lineages (each with 3–9 cases) accounting for over half of locally acquired cases.


3 September


Self WH, Tenforde MW, Stubblefield WB, et al. Seroprevalence of SARS-CoV-2 Among Frontline Health Care Personnel in a Multistate Hospital Network — 13 Academic Medical Centers, April–June 2020. MMWR. Full-text: http://dx.doi.org/10.15585/mmwr.mm6935e2

Many appear to go undetected: among 3,248 HCWs who routinely cared for COVID-19 patients in 13 US academic medical centers from February 1, 2020, 194 (6%) had evidence of previous SARS-CoV-2 infection, with considerable variation by location that generally correlated with community cumulative incidence. Among 194 participants who had SARS-CoV-2 antibodies, 56 (29%) did not recall any symptoms consistent with an acute viral illness in the preceding months and 133 (69%) did not have a previous positive test result demonstrating an acute SARS-CoV-2 infection. Prevalence of SARS-CoV-2 antibodies was lower among personnel who reported always wearing a face covering while caring for patients (6%), compared with those who did not (9%).


4 September


Lordan R, FitzGerald GA, Grosser T. Reopening schools during COVID-19. Science 04 Sep 2020: Vol. 369, Issue 6508, pp. 1146. Full-text: https://doi.org/10.1126/science.abe5765

A note from daily practice. On Thursday, September 3, at our infectious disease clinic in Hamburg, Germany, we found a young male teacher (under 40 years old) to be PCR positive. For the previous three days, he had given lectures to at least 12 classes, despite having (mild) symptoms. How to avoid, how to deal with this situation? This editorial gives some answers, recommending different mitigation strategies for the re-opening of schools.


The national COVID-19 outbreak monitoring group. COVID-19 outbreaks in a transmission control scenario: challenges posed by social and leisure activities, and for workers in vulnerable conditions, Spain, early summer 2020. Eurosurveillance Volume 25, Issue 35, 03/Sep/2020. Full-text: https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2020.25.35.2001545

From mid-June to 2 August, excluding single household outbreaks, 673 outbreaks were notified in Spain. There were two main settings where over 55% of active outbreaks (303/551) and over 60% (3,815/6,208) of active outbreak cases originated: First, social settings such as family gatherings or private parties (112 outbreaks, 854 cases), followed by those linked to leisure venues such as bars, restaurants, or clubs (34 outbreaks, over 1,230 cases). Second, occupational settings (representing 20% of all active outbreaks), mainly among workers in the fruit and vegetable sector (31 outbreaks and around 500 cases) and workers at slaughterhouses or meat processing plants (12 outbreaks and around 360 cases).


6 September


Barbarossa MV, Fuhrmann J, Meinke JH, et al. Modeling the spread of COVID-19 in Germany: Early assessment and possible scenarios. PLoS One. 2020 Sep 4;15(9):e0238559. PubMed: https://pubmed.gov/32886696. Full-text: https://doi.org/10.1371/journal.pone.0238559

Maria Vittoria Barbarossa and colleagues have used complex mathematical models to reproduce data of the early evolution of the COVID-19 outbreak in Germany, taking into account the effect of actual and hypothetical non-pharmaceutical interventions. Interesting finding: a partial (and gradual) lifting of introduced control measures could soon be possible if accompanied by further increased testing activity, strict isolation of detected cases, and reduced contact to risk groups. However, in scenarios without appropriate measures, simulations predict incredibly high peaks in active cases and alarmingly high numbers of deaths far into the future. If no restrictive measures and interventions were to be (re)introduced, the simulation of the model results in about 32 million total infections and 730,000 deaths over the course of the epidemic, which seems to occur only by the end of the summer 2021 under the assumption that no reliable treatment becomes available by then. Just saying.


Marossy A, Rakowicz S, Bhan A, et al. A study of universal SARS-CoV-2 RNA testing of residents and staff in a large group of care homes in South London. J Infect Dis. 2020 Sep 5:jiaa565. PubMed: https://pubmed.gov/32889532. Full-text: https://doi.org/10.1093/infdis/jiaa565

One of the largest studies of care homes in Europe, involving 2,455 individuals tested irrespective of symptoms. Combined nose and throat swab testing for SARS-CoV-2 RNA was carried out in residents and staff across 37 care homes in the London Borough of Bromley across a three-week period. Overall, the point prevalence of SARS-CoV-2 infection was 6.5% with a higher rate in residents (9.0%) than in staff (4.7%). A key finding was the high proportion of asymptomatic infection detected in staff (69%) and residents (51%) with evidence of under-detection of symptoms by care home staff.


7 September


Khan A, Bieh KL, El-Ganainy A, et al. Estimating the COVID-19 Risk during the Hajj Pilgrimage.  Journal of Travel Medicine, 05 September 2020. Full-text: https://doi.org/10.1093/jtm/taaa157

The Hajj, which is held in Makkah, Kingdom of Saudi Arabia (KSA), attracts around 2.5 million Muslim pilgrims from over 150 countries annually. Based on risk estimates, the Ministry of Hajj and Umra announced a reduction in the number of pilgrims and the exclusion of foreign pilgrims from the 2020 Hajj. This was probably a wise decision: The authors calculate that the existing number of designated ward and ICU beds in the Hajj areas would be saturated once the total Hajj population exceeds around 10-15% of the previous five years’ average.


Nayar KR, Koya SF, Ramakrishnan V, et al. Call to avert acceleration of COVID-19 from India’s Sabarimala pilgrimage of 25 million devotees. Journal of Travel Medicine, 05 September 2020, taaa153. Full-text: https://doi.org/10.1093/jtm/taaa153

The next problem. The forthcoming Sabarimala annual Hindu pilgrimage of 41 days duration normally held during the months of November to December at the Sabarimala peak in India is attended by (yes, the number is correct) an average of 25 million pilgrims.  Currently, for the routine non-mass gathering visits to Sabarimala, the State Government requires all pilgrims to submit a negative SARS-CoV-2 antigen test result through the online queue system. But this may be impractical and insufficient when 25 million devotees or more congregate during the annual pilgrimage. Unlike the Hajj pilgrimage (see above) which is international, quota based and restricted through the visa process, participation in Sabarimala pilgrimage, being a domestic event, is uncoordinated and required no registration for participation until last year. The authors discuss the options.


Moreland A, Herlihy C, Tynan MA, et al. Timing of State and Territorial COVID-19 Stay-at-Home Orders and Changes in Population Movement – United States, March 1-May 31, 2020. MMWR Morb Mortal Wkly Rep. 2020 Sep 4;69(35):1198-1203. PubMed: https://pubmed.gov/32881851 . Full-text: https://doi.org/10.15585/mmwr.mm6935a2

People are compliant to mandatory stay-at-home orders. Based on location data from mobile devices, in 97.6% of counties these orders were associated with decreased median population movement after the order start date, relative to the period before the order was implemented.