• Viral Load of #SARS-CoV-2 in Respiratory #Aerosols Emitted by #COVID-19 Patients while Breathing, Talking, and Singing | Clinical Infectious Diseases | Oxford Academic
    https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab691/6343417

    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.

    Although SARS-CoV-2 from saliva and respiratory swabs can be isolated using classical Vero E6 cells, a more sensitive culture assay using Vero E6 TMPRSS2 cells may be superior for culturing virus from patient aerosol samples. Human bronchial epithelial cells may also be more susceptible to infection with wildtype viruses than Vero cells [24]. Further efforts to identify optimal culture methods for exhaled breath and environmental samples are warranted.

    #charge_virale