Top 10: April 2020

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By Christian Hoffmann &
Bernd S. Kamps

30 April

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First, admire a fantastic graphical review on current vaccine development; learn that a still-to-be-published clinical trial on remdesivir reminds Anthony Fauci of the AZT discovery in the 1980s (ask you 60+ year-old colleagues what that means); and discover which New York City borough had the highest rate COVID-19-related hospitalization and death.

Furthermore, discover where have the STEMIs gone during COVID-19; investigate patients with immune-mediated inflammatory disease (rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, psoriasis, inflammatory bowel disease, or related conditions) and confirmed or highly suspected symptomatic Covid-19; create a negative-pressure aerosol cover made out of readily available operating room materials; and explain an increase of out-of-hospital cardiac arrest in the four North-Italian provinces of Lodi, Cremona, Pavia, and Mantua.

Finally, analyze the first ever published randomized, double-blind, placebo-controlled trial of remdesivir (no difference in time to clinical improvement) and listen to Bill Gates talking about a once-in-a-century pandemic and billions of dollars.

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29 April

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First, do research in the patient’s toilet area, determine the seropositivity rate in a large homeless shelter in Boston and find out if pregnant mothers transmit SARS-CoV- to their newborns.

Thereafter, assess acute antibody responses in 285 patients (14% of whom were treated in ICUs), read a review about coagulation abnormalities in COVID-19 patients and check if statin therapy could improve the clinical course of patients with COVID-19.

Finally, examine five cases of large-vessel stroke in patients 33 to 49 years old and discuss with your colleagues the current knowledge on the risk during intubation.

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28 April

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First, find out how mobile phone data can help to better target and design measures to contain and slow the spread of the COVID-19 pandemic, and why SARS-CoV-2 is most likely adapted better to humans than SARS-CoV-1.

Thereafter, enquire the natural history and transmission of SARS-CoV-2 infection, define the incubation period, and assess the secondary attack rate; discuss what we know about COVID-19 protective immunity; and consider serological testing of vaccine trial participants.

Finally, discover the proportions of COVID-19-exposed health care workers with symptoms of depression, anxiety, insomnia and distress; and manage a 73-year-old man with hypertension and chronic obstructive pulmonary disease who has had a fever (maximal temperature, 38.3°C) and a dry cough for the past 2 days.

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27 April

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First, review 6000+ Chinese patient records and find that many survivors had been suffering from chronic heartburn and were on famotidine. Then test people in homeless shelter – if you have more than one positive case, you are likely to have a cluster.

Thereafter, check if living at an altitude of above 3,000 m makes you less susceptible to SARS-CoV-2 infection, if old-fashioned vaccines work in rhesus macaques and who did not become infected in an outbreak in a pediatric dialysis unit.

Finally, measure viral RNA in different body fluids and interpret the presence of nucleic acid, follow the seroconversion patterns of IgM and IgG antibodies in  41 patients and guess how many Bioethics Program Directors did not have ventilator triage policies.

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26 April

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Today, we have adverse winds for Chloroquine (a randomized clinical trial was terminated by the data safety monitoring board after enrolling 81/440 individuals) and hydroxychloroquine (from a case series of 17 systemic lupus erythematosus patients).

Furthermore, papers about the devastation COVID-19 can inflict to organs other than the lung, tobacco smoking which might increase the risk for viral binding and entry of SARS-CoV-2 in lungs of smokers, and about other topics of concern such as muscle atrophy and weakness, mental problems and cognitive impairment after leaving long-term intensive care. And CARDs may not be ARDS.

Finally, good news from 21 healthcare workers who had contact with an initially undiagnosed COVID-19 case.

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25 April

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Dai W, Zhang B, Su H, et al. Structure-based design of antiviral drug candidates targeting the SARS-CoV-2 main protease. Science. 2020 Apr 22. pii: science.abb4489. PubMed: . Full-text:

More on a key enzyme, SARS-CoV-2’s main protease (Mpro). Authors synthesized two lead compounds (11a and 11b) targeting Mpro, exhibiting good inhibitory activity, good PK properties and low toxicity in animal experiments. Pre-clinical.

24 April

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Chorin E, Dai M, Shulman E. The QT interval in patients with COVID-19 treated with hydroxychloroquine and azithromycin. Nature Medicine. Published: 24 April 2020. Full-Text:

Check ECG if you do this! In this important study, authors followed the corrected QT (QTc) interval in a consecutive cohort of 84 patients receiving hydroxychloroquine and azithromycin which were administered orally for 5 days. A prolongation of the QTc from a baseline average of 435 ± 24 ms to a maximal average value of 463 ± 32 ms was found, occurring on day 3.6 ± 1.6 of therapy. In a subset of nine (11%) patients, the QTc was severely prolonged to >500 ms, a known marker of high risk of malignant arrhythmia and sudden cardiac death. Five of nine patients with severe QTc prolongation had a normal QTc at baseline.

23 April

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Cowling BJ, Ali ST, Ng TWY, et al. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health. 2020 Apr 17. pii: S2468-2667(20)30090-6. PubMed: Full-text:

Detailed paper from Hong Kong modelling the effects of non-pharmaceutical interventions (NPIs, including border restrictions, quarantine and isolation, distancing, and changes in population behaviour). NPIs were associated with reduced transmission of COVID-19 and were also likely to have substantially reduced influenza transmission. Findings strongly suggest that social distancing and population behavioural changes – that have a social and economic impact that is less disruptive than a total  lockdown – can  meaningfully  control COVID-19.

22 April

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Cowling BJ, Ali ST, Ng TWY, et al. Impact assessment of non-pharmaceutical interventions against coronavirus disease 2019 and influenza in Hong Kong: an observational study. Lancet Public Health. 2020 Apr 17. pii: S2468-2667(20)30090-6. PubMed: Full-text:

Detailed paper from Hong Kong modelling the effects of non-pharmaceutical interventions (NPIs, including border restrictions, quarantine and isolation, distancing, and changes in population behaviour). NPIs were associated with reduced transmission of COVID-19 and were also likely to have substantially reduced influenza transmission. Findings strongly suggest that social distancing and population behavioural changes – that have a social and economic impact that is less disruptive than a total  lockdown – can  meaningfully  control COVID-19.

20 April

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Today, discover a phantastic overview about current knowledge and the pathways leading to cytokine release syndrome, a report of five patients with COVID-19–associated Guillain–Barré syndrome, a paper on neurological complications which are probably due to an aberrant immune response, and an animal study showing that SARS-CoV-2-infected macaques provide a new model to test therapeutic strategies.

Furthermore, you’ll find that the tighter you control the infected, the less restriction you have to impose on the uninfected and that mass masking  for  source  control  is  a  useful  and   low-cost   adjunct   to   social   distancing   and   hand   hygiene. You’ll be advised not to stop your sartans or ACE inhibitors and find guidance for management of inflammatory bowel disease during the COVID-19.

Finally, it’s not only age. A Multivariate analysis of a retrospective cohort of 1590 hospitalized subjects with COVID-19 throughout China revealed the following factors associated with mortality: age 75 or, age 65-74 years, coronary heart disease, cerebrovascular disease, dyspnea,  procalcitonin>0.5ng/ml, AST>40 U/L. Nothing truly new, the paper reports the largest cohort so far.

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19 April

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Chow EJ, Schwartz NG, Tobolowsky FA, et al. Symptom Screening at Illness Onset of Health Care Personnel With SARS-CoV-2 Infection in King County, Washington. JAMA. 2020 Apr 17. pii: 2764953. PubMed: Full-text:

Detailed analysis of symptoms of all laboratory-confirmed SARS-CoV-2 infections in HCP residing in King County. Ccreening only for fever, cough, short-ness of breath, or sore throat might have missed 17% of symptomatic HCP at the time of illness onset; expanding criteria for symptoms screening to include myalgias and chills may still have missed 10%.

18 April

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Anfinrud P, Stadnytskyi V, Bax CE, Bax A. Visualizing speech-generated oral fluid droplets with laser light scattering. N Engl J Med.

You remember Depeche Mode’s hit ‘Enjoy the Silence’? Then look at this video, a person saying “stay healthy”, a laser light-scattering experiment in which speech-generated droplets and their trajectories were visualized. The louder the speech, the higher the numbers of flashes. The number of flashes was highest when the “th” sound in the word “healthy” was pronounced. Depeche Mode were right: “Words are very unnecessary/They can only do harm”.

17 April

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He X, Lau EHY, Wu P, et al. Temporal dynamics in viral shedding and transmissibility of COVID-19. Nat Med. 2020 Apr 15. pii: 10.1038/s41591-020-0869-5. PubMed: Full-text:

Important work on viral shedding: this may begin 2 to 3 days before the appearance of the first symptoms and infectiousness profile may more closely resemble that of influenza than of SARS.  Analyzing a total of 414 throat swabs in 94 patients, highest viral load in throat swabs was found at the time of symptom onset. Infectiousness started from 2.3 days (95% CI, 0.8–3.0 days) before symptom onset and peaked at 0.7 days (95% CI, −0.2–2.0 days) before symptom onset. Authors estimated that 44% (95%CI 25-69%) of secondary cases were infected during the index cases´ presymptomatic stage. Infectiousness was estimated to decline quickly within 7 days.

16 April

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Comment on
Compassionate Use of Remdesivir for Patients with Severe Covid-19
N Engl J Med. 2020 Apr 10.

Today, we will not discuss the Top Ten Papers. Instead, we will talk about remdesivir and give you 10 good reasons to be careful.


15 April

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Gudbjartsson DF, Helgason A, Jonsson H, et al. Spread of SARS-CoV-2 in the Icelandic Population. N Engl J Med. 2020 Apr 14. PubMed: Full-text:

SARS-CoV-2 in Iceland. As of April 4, a total of 1,221 of 9,199 tested persons (13.3%) were positive. Why is this of interest? Because the country serves as a perfect epidemiological model. Key findings: The percentage of participants who tested positive in population screening remained stable (0.8%) in March, and the infection rates in two screening groups (recruited through open invitation and through random sampling) were not substantially different. Notably, 43% of the participants who tested positive reported having no symptoms.

14 April

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Monteil V, Kwon H, Patricia Prado P, et al. Inhibition of SARS-CoV-2 infections in engineered human tissues using clinical-grade soluble human ACE2. Cell 2020. DOI: 10.1016/j.cell.2020.04.004.

This study shows that human recombinant soluble ACE2 (hrsACE2) blocks SARS-CoV-2 infections of different cells, human blood vessel organoids and human kidney organoids. In ARDS patients, hrsACE2 was ineffective but safe at a broad range of doses. Apeiron Biologics plans a randomized study on 200 COVID-19 patients in April.

13 April

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Gao Y, Yan L, Huang Y, et al. Structure of the RNA-dependent RNA polymerase from COVID-19 virus. Science. 2020 Apr 10. pii: science.abb7498. PubMed: Full-text:

Using cryogenic electron microscopy, authors describe the structure of the RNA-dependent RNA polymerase, another central enzyme of the viral replication machinery. It is also shown how remdesivir and sofosbuvir bind to this polymerase.

12 April

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Wang Q, Zhang Y, Wu L, et al. Structural and Functional Basis of SARS-CoV-2 Entry by Using Human ACE2. Cell. 2020 Apr 7. pii: S0092-8674(20)30338-X. PubMed: . Full-text:

Atomic details of the crystal structure of the C-terminal domain of SARS-CoV-2 spike protein in complex with human ACE2 are presented. hACE2-binding mode of SARS-CoV-2 seems to be similar to SARS-CoV, but some key residue substitutions slightly strengthen the interaction and lead to higher affinity for receptor binding. Antibody experiments indicated notable differences in antigenicity between SARS-CoV and SARS-CoV-2.

11 April

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Wang X, Xu W, Hu G, et al. SARS-CoV-2 infects T lymphocytes through its spike protein-mediated membrane fusion. Cell Mol Immunol. 2020 Apr 7. pii: 10.1038/s41423-020-0424-9. PubMed: . Full-text:

It remains unclear whether SARS-CoV-2 can also infect T cells, resulting in lymphocytopenia. Using a model with pseudoviruses, authors showed that SARS-CoV-2 infects (but does not replicate in) T cells through S protein-mediated membrane fusion. T-cell lines were significantly more sensitive to SARS-CoV-2 infection when compared with SARS-CoV. Of note, a very low expression level of hACE2 was found, indicating that a novel receptor might mediate SARS-CoV-2 entry into T cells.

10 April

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Lechien JR, Chiesa-Estomba CM, De Siati DR, et al. Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study. Eur Arch Otorhinolaryngol. 2020 Apr 6. pii: 10.1007/s00405-020-05965-1. PubMed: Full-text:

This important study shows that in Europe, otolaryngological symptoms are much more common than in Asia (it remains unclear whether this is a true difference). Among 417 mild-to-moderate COVID-19 patients (from 12 European hospitals), 86% and 88% reported olfactory and gustatory dysfunctions, respectively. The vast majority was anosmic (hyposmia, parosmia, phantosmia did also occur), and the early olfactory recovery rate was 44%. Females were more affected than males. Olfactory dysfunction appeared before (12%), at the same time (23%) or after (65%) the appearance of other symptoms. There is no doubt that sudden anosmia or ageusia need to be recognized as important symptoms of COVID-19.

9 April

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Cheung KS, Hung IF, Chan PP, et al. Gastrointestinal Manifestations of SARS-CoV-2 Infection and Virus Load in Fecal Samples from the Hong Kong Cohort and Systematic Review and Meta-analysis. Gastroenterology. 2020 Apr 3. pii: S0016-5085(20)30448-0. PubMed: . Full-text:

In a meta-analysis of 60 studies, comprising 4,243 patients, the pooled prevalence of gastrointestinal symptoms was 17.6% (95% CI, 12.3%-24.5%). Prevalence was lower in studies from China than other countries. Pooled prevalence of stool samples that were positive for virus RNA was 48.1% and could persist for up to ≥33 days from illness onset even after viral RNA negativity in respiratory specimens. Stool viral RNA was detected at higher frequency among those with diarrhea.

8 April

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Duan K, Liu B, Li C, et al. Effectiveness of convalescent plasma therapy in severe COVID-19 patients. PNAS 2020, April 6.

A single dose (200 mL) of convalescent plasma was given to 10 patients (9 treated with umifenovir, 6 with methylprednisolone, 1 with remdesivir). In all 7 patients with viremia, serum SARS-CoV-2 RNA decreased to an undetectable level within 2-6 days. Meanwhile, clinical symptoms and paraclinical criteria rapidly improved within three days. Using antibodies from convalescents could be an option in severe cases. It’s now time for larger studies.

7 April

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Grasselli G, Zangrillo A, Zanella A, et al. Baseline Characteristics and Outcomes of 1591 Patients Infected With SARS-CoV-2 Admitted to ICUs of the Lombardy Region, Italy. JAMA. 2020 Apr 6. PubMed: Full-text: work, providing sobering evidence about the burden of critical illness. Over a period of 28 days, 1,591 COVID-19 patients (88 % requiring endotracheal intubation and ventilatory support) were admitted to 72 Italian ICUs, an average of 22 patients per ICU (median length of stay was 9 days). Of note, 82 % were male and median age was only 63 years (IQR 56-70), suggesting that older age alone is not a risk factor for admission to the ICU. As of March 25, ICU mortality was 26 %. However, 58 % were still in the ICU. Scarifying study, telling us a lot about the fragility of health care systems in even the wealthiest countries.

5 April

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Bavishi C, Maddox TM, Messerli FH. Coronavirus Disease 2019 (COVID-19) Infection and Renin Angiotensin System Blockers. JAMA Cardiol. 2020 Apr 3. pii: 2764299. PubMed: Full-text:

This mini-review outlines the mechanisms by which RAAS inhibitors (ACEIs/ARBs) may be of benefit in COVID-19. Overview of the current recommendations for their use in infected patients. According to the authors, the biological plausibility of salutary effects of RAAS inhibitors is intriguing and several trials of starting losartan in patients with COVID-19 are currently being planned.

4 April

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Leung NH, Chu Dk, Shiu EY. Respiratory virus shedding in exhaled breath and efficacy of face masks. Nature Med 2020, April 3.

Do face masks work? Yes, but it depends. This important study from Hong Kong (performed 2013-16) quantified virus in respiratory droplets and aerosols in exhaled breath. In total, 111 participants (infected with seasonal coronavirus, influenza or rhinovirus) were randomized to wear (or not) a simple surgical face mask. Results suggested that masks could be used by ill people to reduce onward transmission. But note the small numbers: in respiratory droplets, seasonal coronavirus was found in 0/11 droplets (aerosols: 0/11) from participants wearing face masks, compared to 3/10 (aerosols: 4/10) without masks. Influenza viruses were detected in 1/27 (aerosols 6/27!) with face masks, compared to 6/23 (8/23) without. For rhinovirus, there were no significant differences at all. Of note, authors also identified virus in some participants who did not cough at all during the 30-min exhaled breath collection, suggesting droplet and aerosol routes of transmission from individuals with no obvious signs or symptoms.

3 April

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Shang J, Ye G, Shi K. Structural basis of receptor recognition by SARS-CoV-2. Nature 2020, March 30.

How well does SARS-CoV-2 recognize hACE2? Better than other coronaviruses. Compared to SARS-CoV and RaTG13 (isolated from bats), ACE2-binding affinity is higher. Functionally important epitopes in SARS-CoV-2 RBM are described that can potentially be targeted by neutralizing antibody drugs.

2 April

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Wölfel R, Corman VM, Guggemos W. et al. Virological assessment of hospitalized patients with COVID-2019. Nature 2020, April 1. Full-text:

Important work, showing active virus replication in upper respiratory tract tissues (in contrast to SARS). In a detailed virological analysis of nine cases, pharyngeal virus shedding was very high during the first week of symptoms (peak at 7.11 × 108 RNA copies per throat swab, day 4), more than 1000 times higher than seen with SARS-CoV. Infectious virus was readily isolated from throat- and lung-derived samples, but not from stool samples, in spite of high virus RNA concentration. Blood and urine never yielded virus. Shedding of viral RNA from sputum outlasted the end of symptoms.

1 April

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Yazdany J, Kim AH. Use of Hydroxychloroquine and Chloroquine During the COVID-19 Pandemic: What Every Clinician Should Know. Ann Intern Med. 2020. DOI: 10.7326/M20-1334. Full-text:

Extensive comment on someone’s swanky twitter claiming that the combination of HCQ and azithromycin has “a real chance to be one of the biggest game changers in the history of medicine” (March 21). Careful review about the risks of HCQ and how pretentious dissemination of overpromised data may cause severe harm.

31 March

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Yu F, Yan L, Wang N, et al. Quantitative Detection and Viral Load Analysis of SARS-CoV-2 in Infected Patients. Clin Infect Dis. 2020 Mar 28. pii: 5812997. PubMed: Full-text:

Is sputum sufficient for diagnosis? In a total of 323 samples from 76 pts, the average viral load in sputum (17429 copies/test) was significantly higher than in throat swabs (2552) and nasal swabs (651). Viral load was also higher in the early and progressive stages than in the recovery stage. If these data were confirmed, collection of specimen would be much easier.

30 March

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McMichael TM, Currie DW, Clark S, et al. Epidemiology of Covid-19 in a Long-Term Care Facility in King County, Washington. N Engl J Med. 2020 Mar 27. PubMed: Full-text:

Important paper that highlights the severity of COVID-19 in older people. A total of 167 confirmed cases affecting 101 residents in a long-term care facility, 50 health care personnel (HCP), and 16 visitors. The case fatality rate for residents was 33.7% (34 of 101) and 0 % among HCP.

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