tetano
Editor, Senior Moderator
Clin Infect Dis
. 2021 Aug 6;ciab691.
doi: 10.1093/cid/ciab691. Online ahead of print.
Viral Load of SARS-CoV-2 in Respiratory Aerosols Emitted by COVID-19 Patients while Breathing, Talking, and Singing
Kristen K Coleman[SUP] 1 [/SUP], Douglas Jie Wen Tay[SUP] 2 [/SUP], Kai Sen Tan[SUP] 3 4 5 6 [/SUP], Sean Wei Xiang Ong[SUP] 7 8 [/SUP], Than The Son[SUP] 1 2 [/SUP], Ming Hui Koh[SUP] 2 [/SUP], Yi Qing Chin[SUP] 7 [/SUP], Haziq Nasir[SUP] 9 [/SUP], Tze Minn Mak[SUP] 7 [/SUP], Justin Jang Hann Chu[SUP] 3 5 6 10 [/SUP], Donald K Milton[SUP] 11 [/SUP], Vincent T K Chow[SUP] 3 5 [/SUP], Paul Anantharajah Tambyah[SUP] 5 9 [/SUP], Mark Chen[SUP] 7 8 [/SUP], Tham Kwok Wai[SUP] 2 [/SUP]
Affiliations
Abstract
Background: Multiple SARS-CoV-2 superspreading events suggest that aerosols play an important role in driving the COVID-19 pandemic. To better understand how airborne SARS-CoV-2 transmission occurs, we sought to determine viral loads within coarse (>5μm) and fine (≤5μm) respiratory aerosols produced when breathing, talking, and singing.
Methods: Using a G-II exhaled breath collector, we measured viral RNA in coarse and fine respiratory aerosols emitted by COVID-19 patients during 30 minutes of breathing, 15 minutes of talking, and 15 minutes of singing.
Results: Thirteen participants (59%) emitted detectable levels of SARS-CoV-2 RNA in respiratory aerosols, including 3 asymptomatic and 1 presymptomatic patient. Viral loads ranged from 63-5,821 N gene copies per expiratory activity per participant, with high person-to-person variation. Patients earlier in illness were more likely to emit detectable RNA. Two participants, sampled on day 3 of illness, accounted for 52% of the total viral load. Overall, 94% of SARS-CoV-2 RNA copies were emitted by talking and singing. Interestingly, 7 participants emitted more virus from talking than singing. Overall, fine aerosols constituted 85% of the viral load detected in our study. Virus cultures were negative.
Conclusions: Fine aerosols produced by talking and singing contain more SARS-CoV-2 copies than coarse aerosols and may play a significant role in SARS-CoV-2 transmission. Exposure to fine aerosols, especially indoors, should be mitigated. Isolating viable SARS-CoV-2 from respiratory aerosol samples remains challenging, and whether this can be more easily accomplished for emerging SARS-CoV-2 variants is an urgent enquiry necessitating larger-scale studies.
Keywords: COVID-19; SARS-CoV-2; aerosol transmission; airborne transmission; respiratory virus transmission; severe acute respiratory syndrome coronavirus 2.
. 2021 Aug 6;ciab691.
doi: 10.1093/cid/ciab691. Online ahead of print.
Viral Load of SARS-CoV-2 in Respiratory Aerosols Emitted by COVID-19 Patients while Breathing, Talking, and Singing
Kristen K Coleman[SUP] 1 [/SUP], Douglas Jie Wen Tay[SUP] 2 [/SUP], Kai Sen Tan[SUP] 3 4 5 6 [/SUP], Sean Wei Xiang Ong[SUP] 7 8 [/SUP], Than The Son[SUP] 1 2 [/SUP], Ming Hui Koh[SUP] 2 [/SUP], Yi Qing Chin[SUP] 7 [/SUP], Haziq Nasir[SUP] 9 [/SUP], Tze Minn Mak[SUP] 7 [/SUP], Justin Jang Hann Chu[SUP] 3 5 6 10 [/SUP], Donald K Milton[SUP] 11 [/SUP], Vincent T K Chow[SUP] 3 5 [/SUP], Paul Anantharajah Tambyah[SUP] 5 9 [/SUP], Mark Chen[SUP] 7 8 [/SUP], Tham Kwok Wai[SUP] 2 [/SUP]
Affiliations
- PMID: 34358292
- DOI: 10.1093/cid/ciab691
Abstract
Background: Multiple SARS-CoV-2 superspreading events suggest that aerosols play an important role in driving the COVID-19 pandemic. To better understand how airborne SARS-CoV-2 transmission occurs, we sought to determine viral loads within coarse (>5μm) and fine (≤5μm) respiratory aerosols produced when breathing, talking, and singing.
Methods: Using a G-II exhaled breath collector, we measured viral RNA in coarse and fine respiratory aerosols emitted by COVID-19 patients during 30 minutes of breathing, 15 minutes of talking, and 15 minutes of singing.
Results: Thirteen participants (59%) emitted detectable levels of SARS-CoV-2 RNA in respiratory aerosols, including 3 asymptomatic and 1 presymptomatic patient. Viral loads ranged from 63-5,821 N gene copies per expiratory activity per participant, with high person-to-person variation. Patients earlier in illness were more likely to emit detectable RNA. Two participants, sampled on day 3 of illness, accounted for 52% of the total viral load. Overall, 94% of SARS-CoV-2 RNA copies were emitted by talking and singing. Interestingly, 7 participants emitted more virus from talking than singing. Overall, fine aerosols constituted 85% of the viral load detected in our study. Virus cultures were negative.
Conclusions: Fine aerosols produced by talking and singing contain more SARS-CoV-2 copies than coarse aerosols and may play a significant role in SARS-CoV-2 transmission. Exposure to fine aerosols, especially indoors, should be mitigated. Isolating viable SARS-CoV-2 from respiratory aerosol samples remains challenging, and whether this can be more easily accomplished for emerging SARS-CoV-2 variants is an urgent enquiry necessitating larger-scale studies.
Keywords: COVID-19; SARS-CoV-2; aerosol transmission; airborne transmission; respiratory virus transmission; severe acute respiratory syndrome coronavirus 2.