covid: aerosol spread, worse with variants; masks important
A couple of articles have just come out on airborne transmissibility of SARS-CoV-2. The first study quantifies airborne viral transmission (see covid more aerosol spread clininfdis2021 in dropbox, or doi.org/10.1093/cid/ciab691) Details: -- 22 patients PCR-positive Covid-19 patients in Singapore were recruited for evaluation of respiratory aerosols, divided into coarse (>5 µm) and fine ( ≤ 5 µm) aerosols -- 19 (86%) male, median age 38, 5 (23%) asymptomatic -- symptoms: fever (10 people), rhinorrhea (8), sore throat (6), cough (5) -- almost all had PCR Ct values in the mid-teens, one asymptomatic had Ct 22 (these represent very high viral loads), and another had Ct 33 (lower viral load, on day 3 of diagnosis, though unclear how long they had been positive given lack of symptoms) -- patients were seated and their expiratory breath was sampled, with 30 minutes of tidal breathing, 15 minutes of talking, and 15 minutes of singing Results...