2/24—Age groups that sustain resurging COVID-19 epidemics
Age groups that sustain resurging COVID-19 epidemics in the United States
We analyze aggregated, age-specific mobility trends from more than 10 million individuals in the US and link these mechanistically to age-specific COVID-19 mortality data. We estimate that as of October 2020, individuals aged 20-49 are the only age groups sustaining resurgent SARS-CoV-2 transmission with reproduction numbers well above one, and that at least 65% of COVID-19 infections originate from individuals aged 20-49 in the US.
FDA review confirms safety, efficacy of single-shot Johnson & Johnson coronavirus vaccine, especially against severe cases
[Media report; see also FDA briefing document.] A third coronavirus vaccine could soon be available in the United States, a one-shot regimen made by Johnson & Johnson that proved safe and effective in a clinical trial and completely protective against hospitalizations and deaths, according to a Food and Drug Administration review released Wednesday.
Lessons from applied large-scale pooling of 133,816 SARS-CoV-2 RT-PCR tests
Pooling multiple swab samples prior to RNA extraction and real-time reverse-transcription (RT-PCR) analysis has been proposed as a strategy to reduce costs and increase throughput of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) tests. Here we report an analysis of 133,816 samples collected between April-September 2020 and tested by Dorfman pooling for the presence of SARS-CoV-2. We spared 76% of RNA extraction and RT-PCR tests, despite the frequently changing prevalence (0.5%-6%). We observed pooling efficiency and sensitivity that exceeded theoretical predictions, which resulted from the non-random distribution of positive samples in pools. Overall, our findings support the use of pooling for efficient large-scale SARS-CoV-2 testing.
Hydrating the respiratory tract: an alternative explanation why masks lower severity of COVID-19
We demonstrate that normal breathing results in an absorption-desorption cycle inside facemasks. For double-layered cotton masks, the effective increase in relative humidity can exceed 100%. We propose that the recently reported, disease-attenuating effect of generic facemasks is dominated by the strong humidity increase of inspired air. This elevated humidity promotes mucociliary clearance of pathogens from the lungs, both before and after an infection of the upper respiratory tract has occurred. Effective mucociliary clearance can delay and reduce infection of the lower respiratory tract, thus mitigating disease severity. This mode of action suggests that masks can benefit the wearer even after an infection in the upper respiratory tract has occurred, complementing the traditional function of masks to limit person-to-person disease transmission.
COVID-19 epidemiology: evidence, risks, and misconceptions
In-depth review (1 hour) and practical applications by John P.A. Ioannidis, MD, DSc, Professor of Medicine, Epidemiology and Population Health, Biomedical Data Science and Statistics Stanford University.
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