Top 10: February 23

Copy-editor: Rob Camp


Paper of the Day

Wang Z, Galea ER, Grandison A, et al. Inflight Transmission of COVID-19 Based on Experimental Aerosol Dispersion Data. Journal of Travel Medicine, February 19, 2021. taab023,

No nuts on planes. This elegant analysis demonstrated that while there is a significant reduction in aerosol concentration due to the nature of the cabin ventilation and filtration system, this does not necessarily mean that there is a low probability or risk of in-flight infection. Main results: 1. The economy cabin exhibits the highest probability of infection. 2. Average risk (without masks) for a 2-hour flight in a B777–200 aircraft ranges from 0.1% to 2.5% and for a 12-hour flight from 0.8% to 10.8%, respectively. 3. If all passengers wear face masks throughout the 12-hour flight, the average infection probability can be reduced by approximately 73%/32% for high/low efficiency masks. 4. If face masks are worn by all passengers except during a one-hour meal service, the average infection probability is increased by 59%/8% compared to the situation where the mask is not removed. Bottom line: Don’t remove your KN95 mask. No nuts, no meals. And better forget your frequent flyer status as long as you are unvaccinated (actually, forget it anyway, we’ll get warm here up north and Zoom works fine).


Bender JK, Brandl M, Höhle M, Buchholz U, Zeitlmann N. Analysis of asymptomatic and presymptomatic transmission in SARS-CoV-2 outbreak, Germany, 2020. Emerg Infect Dis February 18, 2021 Apr [date cited].

Jennifer K. Bender and colleagues determined secondary attack rates (SAR) among close contacts of 46 symptomatic and 7 asymptomatic patients from Southern Germany. Little to no transmission occurred from asymptomatic case-patients. Pre-symptomatic transmission was more frequent than symptomatic transmission.



Kim MC, Cui C, Shin KR, et al. Duration of Culturable SARS-CoV-2 in Hospitalized Patients with Covid-19. N Engl J Med. 2021 Feb 18;384(7):671-673. PubMed: . Full-text:

How long can we find culturable virus? Not beyond day 12. Min-Chul Kim and colleagues from Seoul, Korea, cultured SARS-CoV-2 in serial respiratory samples obtained from 21 hospitalized patients with COVID-19 to assess the duration of shedding of viable virus. The latest positive viral culture was 12 days after symptom onset (in one patient). Viral culture was positive only in samples with a cycle-threshold value of 28.4 or less.



Harritshøj LH, Gybel-Brask M, Afzal S, et al. Comparison of sixteen serological SARS-CoV-2 immunoassays in sixteen clinical laboratories. J Clin Microbiol. 2021 Feb 11:JCM.02596-20. PubMed: Full-text:

This comparative study of 15 commercial and one in-house laboratory serological SARS-CoV-2 assays pinpoints differences in accuracy; most total-Ab and IgG assays (not all), including assays with potential for high-throughput production in automated laboratories, reached pre-defined criteria for acceptable performance. Diagnostic accuracy was higher in the group of the SARS-CoV-2 total Ab assays compared to the group of the SARS-CoV-2 IgG assays.


Al Suwaidi H, Senok A, Varghese R, et al. Saliva for molecular detection of SARS-CoV-2 in school-aged children. Clin Microb Infection, February 19, 2021.

Use saliva in children! For this COVID-19 screening study in Dubai, United Arab Emirates, each child provided paired nasopharyngeal (NP) swab and saliva. Main results: detection in NP swab (16.7%; 81/485) and saliva (15.9%; 77/485) did not differ. Cycle threshold values were significantly higher in NP swab/saliva pairs with discordant findings compared to those with both specimens positive.



Schinkel M, Appelman B, Butler J, et al. Association of clinical sub-phenotypes and clinical deterioration in COVID-19: further cluster analyses. Intensive Care Med (2021). February 18, 2021.

Among patients admitted to ten teaching hospitals across the Netherlands, three sub-phenotypes were identified.

  • Sub-phenotype 1 (n = 592) mainly included females (75%, median age 63), characterized by a high prevalence of gastro-intestinal complaints (84%) and sputum production (63%). Co-morbidities and medication usage were scarce. The composite outcome of ICU admittance/death rates was relatively low (25%).
  • Sub-phenotype 2 (n = 876) included more males (80%, median age 63 years) with few co-morbidities and the lowest medication usage of all three groups. Patients presented with less symptoms than those in sub-phenotype 1, but ICU admittance/death rates were higher (31%).
  • Sub-phenotype 3 (n = 551) mostly consisted of older males (80%, median age 76) with multiple co-morbidities, mainly diabetes (62%), hypertension (88%) and other cardiovascular diseases (72%), and consequent medication usage. Patients reported less symptoms such as dyspnea (67%), headache (9%) and myalgia (12%). ICU admission and/or 21-day mortality occurred in 43%.

The authors believe the main value of these sub-phenotypes lies not with their ability to discriminate between clinical outcomes, but in their potential to understand disease heterogeneity and find more homogeneous patient subgroups that may respond more similarly to certain treatments.


Collateral damage

Fong MW, Leung NHL, Cowling BJ, Wu P. Upper respiratory infections in schools and childcare centers reopening after COVID-19 dismissals, Hong Kong. Emerg Infect Dis, February 17, 2021 (May date cited).

A large number of outbreaks of acute upper respiratory tract infections (URTIs), likely rhinovirus infections, were identified in October–November 2020 in reopened primary schools, secondary schools, kindergartens, childcare centers, and nursery schools in Hong Kong; these outbreaks led to further territory-wide school dismissals for younger children. Increased susceptibility to rhinoviruses during prolonged school closures and dismissals for coronavirus disease and varying effectiveness of nonpharmaceutical interventions may have heightened transmission of cold-causing viruses when school attendance resumed.



Quartuccio L, Treppo E, Binutti M, Del Frate G, De Vita S. Timing of Rituximab and immunoglobulin level influence the risk of death for COVID-19 in ANCA-associated vasculitis. Rheumatology (Oxford). 2021 Feb 20:keab175. PubMed: . Full-text:

SARS-CoV-2 infections in two patients with polyangiitis who had been treated with rituximab. One died, one was asymptomatic. As timing of rituximab and IgG levels were quite different between the two cases, the authors speculate that this conditioned the final outcome greatly.


Severe COVID-19

Shah P, Smith H, Olarewaju A, et al. Is Cardiopulmonary Resuscitation Futile in Coronavirus Disease 2019 Patients Experiencing In-Hospital Cardiac Arrest? Critical Care Medicine: February 2021 – Volume 49 – Issue 2 – p 201-208. Full-text:

Well, probably yes. Out of 1094 COVID-19 patients who were admitted to three hospitals in Georgia, 63 patients suffered from in-hospital cardiac arrest with attempted resuscitation and were included in this study. Although return of spontaneous circulation was achieved in 29% of patients, it was brief in all of them. The in-hospital mortality was 100%.



Ma S, Xu C, Liu S, et al. Efficacy and safety of systematic corticosteroids among severe COVID-19 patients: a systematic review and meta-analysis of randomized controlled trials. Sig Transduct Target Ther 6, 83 (2021).

In this meta-analysis including 7 RCTs and 6250 severe COVID-19 patients, corticosteroid treatment was related to a reduction of all-cause mortality and disease progression, but not with an increase in serious adverse events. Of note, survival benefit was absent if RECOVERY trial was excluded. More robust supporting data are required.

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