Top 10: September 26

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By Christian Hoffmann &
Bernd S. Kamps

26 September


Buss LF, Prete Jr CA, Abrahim CMM, et al. COVID-19 herd immunity in the Brazilian Amazon. medRxiv 2020, posted 21 September. Full-text:

As much as 66% of the population of Manaus (two million people), Brazil, could have been infected with SARS-CoV-2. Ester Sabino, Lewis Buss and colleagues show that the transmission of SARS-CoV-2 in Manaus increased quickly during March and April and declined slowly from May to September. In June, one month following the epidemic peak, 44% of the population was seropositive for SARS-CoV-2. After correcting for confounding factors, the authors estimate the epidemic size to be 66% by early August 2020. Note: these findings have not yet been peer reviewed.

Remember: herd immunity is defined as the proportion of a population that must be immune to an infectious disease, either by natural infection or vaccination, such that new cases decline and R0 falls below 1 (see also


Boehmer TK, DeVies J, Caruso E, et al. Changing Age Distribution of the COVID-19 Pandemic — United States, May–August 2020. MMWR Morb Mortal Wkly Rep. ePub: 23 September 2020. DOI:

First the kids, then the parents and, finally, the grandparents. Tegan Boehmer et al. show that during June–August 2020, COVID-19 incidence was highest in persons aged 20–29 years. Across the southern United States in June 2020, increases in percentage of positive SARS-CoV-2 test results among adults aged 20–39 years preceded increases among those aged ≥ 60 years by 4–15 days. The authors conclude that preventive behavior by younger adults is needed to help reduce infection and subsequent transmission to persons at higher risk for severe illness.



An outbreak in Sallent (72 km from Barcelona) with 30 SARS-CoV-2-infected people demonstrates the risk posed by choirs and karaoke in poorly ventilated places. See the video: Do not sing and jump around in enclosed spaces!



Pierce CA, Preston-Hurlburt P, Dai Y, et al. Immune responses to SARS-CoV-2 infection in hospitalized pediatric and adult patients. Sci Transl Med. 2020 Sep 21:eabd5487. PubMed: Full-text:

Compared to adults, pediatric patients have a shorter length of stay in hospital, a decreased requirement for mechanical ventilation and a lower mortality. Now Betsy Herold and Carl Pierce compared cytokine, humoral, and cellular immune responses in pediatric (children and youth, age < 24 years) (n = 65) and adult (n = 60) patients with COVID-19 at a metropolitan hospital system in New York City. Children had higher serum concentrations of IL-17A and IFN-γ which in adult patients decreased progressively with age. Read more about adult T cell responses, serum neutralizing antibody titers and antibody-dependent cellular phagocytosis.



Cookson C. UK to test vaccines on volunteers deliberately infected with Covid-19. Financial Times 2020, published 23 September. Full-text:  

In the world’s first COVID-19 ‘human challenge trials’ healthy volunteers will be deliberately infected with SARS-CoV-2 to assess the effectiveness of experimental vaccines. See also the CR Top 10, June 4: Jamrozik E, Selgelid MJ. COVID-19 human challenge studies: ethical issues. Lancet Infect Dis. 2020 May 29:S1473-3099(20)30438-2. PubMed: Full-text:

Human challenge studies could accelerate vaccine development, helping to test multiple candidate vaccines. This personal view on ethical issues explains why this will be difficult. The authors argue that human challenge studies can “reasonably be considered ethically acceptable insofar as such studies are accepted internationally and by the communities in which they are done, can realistically be expected to accelerate or improve vaccine development, have considerable potential to directly benefit participants, are designed to limit and minimise risks to participants, and are done with strict infection control measures to limit and reduce third-party risks.”



Zamecnik CR, Rajan JV, Yamauchi KA, et al. ReScan, a Multiplex Diagnostic Pipeline, Pans Human Sera for SARS-CoV-2 Antigens. Cell Reports 2020, published 24 September. Full-text:

Identifying highly specific sets of antigens that are less cross-reactive with antibodies elicited by other common human CoV infections could improve future diagnostic SARS-CoV-2 tests. Here Michael Wilson, Colin Zamecnik and colleagues perform proteome-wide profiling of coronavirus antigens enriched by 98 COVID-19 patient sera and identify 9 antigens derived from 3 SARS-CoV-2 proteins as candidates for more specific, multiplexed SARS-CoV-2 serologic assays. The authors conclude that their proof-of-concept study might have broad applicability for other emerging infectious diseases or autoimmune diseases that lack valid biomarkers. Music from the future?



Muñoz-Price LS, Nattinger AB, Rivera F, et al. Racial Disparities in Incidence and Outcomes Among Patients With COVID-19. JAMA Netw Open 2020, published 25 September. Full-text:

A total of 2595 patients: 785 (30.2%) African-American individuals, 1617 (62.3%) White individuals, and 193 (7.4%) of other racial groups. Silvia Muñoz-Price et al. show that in the first weeks of the COVID-19 pandemic in Milwaukee, Wisconsin, Black race was associated with a positive COVID-19 test and a subsequent need for hospitalization, but only poverty was associated with intensive care unit admission.


Kabarriti R, Brodin P, Maron MI, et al. Association of Race and Ethnicity With Comorbidities and Survival Among Patients With COVID-19 at an Urban Medical Center in New York. JAMA Netw Open 2020, published 25 September. Full-text:

Similar results as the previous study: Andrew Racine, Rafi Kabarriti and colleagues report 5902 SARS-CoV-2 positive patients treated at a single academic medical center in New York. While non-Hispanic Black and Hispanic patients had a higher proportion of more than 2 medical comorbidities, their survival outcomes were at least as good as those of their non-Hispanic White counterparts when controlling for age, sex, and comorbidities.



Pau AK, Aberg J, Baker J, et al. Convalescent Plasma for the Treatment of COVID-19: Perspectives of the National Institutes of Health COVID-19 Treatment Guidelines Panel. Ann Intern Med 2020, published 25 September. Full-text:

The COVID-19 pandemic has intensified the tension between providing rapid access to promising therapies and generating the scientific evidence needed to establish whether those therapies are safe and effective. Here, Alice Pau et al. discuss the use of convalescent plasma for the treatment of COVID-19. They conclude that currently the data are insufficient to recommend for or against convalescent plasma for treating COVID-19.



Panagiotakopoulos L, Myers TR, Gee J, et al. SARS-CoV-2 Infection Among Hospitalized Pregnant Women: Reasons for Admission and Pregnancy Characteristics — Eight U.S. Health Care Centers, March 1–May 30, 2020. MMWR Morb Mortal Wkly Rep 2020;69:1355–1359. DOI:

Some pregnant women are at increased risk for severe illness from SARS-CoV-2 infection. Now Lakshmi Panagiotakopoulos et al. report that 105 hospitalized pregnant women with SARS-CoV-2 infection were identified, including 62 (59%) hospitalized for obstetric reasons (i.e., labor and delivery or other pregnancy-related indication) and 43 (41%) hospitalized for COVID-19 illness without an obstetric reason. Prevalence of pre-pregnancy obesity and gestational diabetes were higher among pregnant women hospitalized for COVID-19–related illness (e.g., worsening respiratory status) than among those admitted for pregnancy-related treatment or procedures (e.g., delivery) and found to have COVID-19. Among the 43 pregnant women hospitalized for COVID-19, 13 (30%) required intensive care unit (ICU) admission, six (14%) required mechanical ventilation, and one died from COVID-19.


Delahoy MJ, Whitaker M, O’Halloran A, et al. Characteristics and Maternal and Birth Outcomes of Hospitalized Pregnant Women with Laboratory-Confirmed COVID-19 — COVID-NET, 13 States, March 1–August 22, 2020. MMWR Morb Mortal Wkly Rep 2020;69:1347–1354. DOI:

One in four women aged 15–49 years who had a COVID-19–associated hospitalization in the US during March 1–August 22, 2020 was pregnant. Now Miranda Delahoy et al. report 598 hospitalized pregnant women with COVID-19 (55% were asymptomatic at admission). Severe illness occurred among symptomatic pregnant women, including intensive care unit admissions (16%), mechanical ventilation (8%), and death (1%). Among all pregnancies completed during a COVID-19–associated hospitalization, 2% resulted in pregnancy losses. Pregnancy losses occurred among both symptomatic and asymptomatic hospitalized women with COVID-19.



Rubin EJ, Baden LR, Morrissey S. Eight Months of Action and Inaction against Covid-19. Audio interview (27:02). N Engl J Med 2020; 383:e95. Access:

The editors reflect on 8 months of action and inaction against COVID-19.



If you read Spanish, read Salas J. El peligro de cantar en interiores en tiempos de covid. El País 2020, published 26 September. Full-text:

Un brote en Sallent de Llobregat con 30 contagiados muestra el riesgo que suponen coros y karaokes por la propagación del virus en el aire al alzar la voz en locales mal ventilado. En vídeo: El grupo de góspel barcelonés:

See also the City Hall announcement (in Catalan): Comunicat de l’Ajuntament de Sallent en relació als casos positius per COVID-19 de la coral The River Troupe Gospel.