Abstract Background SARS-CoV-2 epidemiology implicates airborne transmission; aerosol infectiousness and impacts of masks and variants on aerosol shedding are not well understood. Methods We recruited COVID-19 cases to give blood, saliva, mid-turbinate and fomite (phone) swabs, and 30-minute breath samples while vocalizing into a Gesundheit-II, with and without masks at up to two visits two days apart. We quantified and sequenced viral RNA, cultured virus, and assayed sera for anti-spike and anti-receptor binding domain antibodies. Results We enrolled 49 seronegative cases (mean days post onset 3.8 ±2.1), May 2020 through April 2021. We detected SARS-CoV-2 RNA in 45% of fine (≤5 µm), 31% of coarse (>5 µm) aerosols, and 65% of fomite samples overall and in all samples from four alpha-variant cases. Masks reduced viral RNA by 48% (95% confidence interval [CI], 3 to 72%) in fine and by 77% (95% CI, 51 to 89%) in coarse aerosols; cloth and surgical masks were not significantly different. The alpha variant was associated with a 43-fold (95% CI, 6.6 to 280-fold) increase in fine aerosol viral RNA, compared with earlier viruses, that remained a significant 18-fold (95% CI, 3.4 to 92-fold) increase adjusting for viral RNA in saliva, swabs, and other potential confounders. Two fine aerosol samples, collected while participants wore masks, were culture-positive. Conclusion SARS-CoV-2 is evolving toward more efficient aerosol generation and loose-fitting masks provide significant but only modest source control. Therefore, until vaccination rates are very high, continued layered controls and tight-fitting masks and respirators will be necessary.
【저자키워드】 SARS-CoV-2, Airborne infection, SARS-CoV-2 variants, Face masks, exhaled breath aerosol, 【초록키워드】 viruses, antibodies, Saliva, variant, Masks, aerosol, surgical, variants, Aerosols, Aerosol generation, Mask, Viral, Culture, sera, Impact, swabs, breath, Control, Alpha, SARS-CoV-2 RNA, Viral RNA, Alpha variant, seronegative, Blood, Anti-spike, SARS-CoV-2 epidemiology, respirators, COVID-19 cases, Respirator, 95% CI, 95% confidence interval, COVID-19 case, confounders, participant, binding domain, vaccination rates, cultured virus, vaccination rate, Result, enrolled, collected, sequenced, recruited, remained, reduced, increase in, quantified, not significantly different, 【제목키워드】 Mask,