High SARS-CoV-2 Attack Rate Following Exposure at a Choir Practice - Skagit County, Washington, March 2020.
By L. Hamner, Polly Dubbel, Ian Capron, A. Ross, A. Jordan, Jaxon Lee, Joanne Lynn, A. Ball, S. Narwal, S. Russell and 2 more. MMWR. Morbidity and mortality weekly report, 2020
693 citations recorded by the source corpus.
On March 17, 2020, a member of a Skagit County, Washington, choir informed Skagit County Public Health (SCPH) that several members of the 122-member choir had become ill. Three persons, two from Skagit County and one from another area, had test results positive for SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19). Another 25 persons had compatible symptoms. SCPH obtained the choir's member list and began an investigation on March 18. Among 61 persons who attended a March 10 choir practice at which one person was known to be symptomatic, 53 cases were identified, including 33 confirmed and 20 probable cases (secondary attack rates of 53.3% among confirmed cases and 86.7% among all cases). Three of the 53 persons who became ill were hospitalized (5.7%), and two died (3.7%). The 2.5-hour singing practice provided several opportunities for droplet and fomite transmission, including members sitting close to one another, sharing snacks, and stacking chairs at the end of the practice. The act of singing, itself, might have contributed to transmission through emission of aerosols, which is affected by loudness of vocalization (1). Certain persons, known as superemitters, who release more aerosol particles during speech than do their peers, might have contributed to this and previously reported COVID-19 superspreading events (2-5). These data demonstrate the high transmissibility of SARS-CoV-2 and the possibility of superemitters contributing to broad transmission in certain unique activities and circumstances. It is recommended that persons avoid face-to-face contact with others, not gather in groups, avoid crowded places, maintain physical distancing of at least 6 feet to reduce transmission, and wear cloth face coverings in public settings where other social distancing measures are difficult to maintain.
Subfields: Clinical Psychology, Pulmonary and Respiratory Medicine, Speech and Hearing
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In Pulmonary and Respiratory Medicine
Citations in the corpus
- It is Time to Address Airborne Transmission of COVID-19 (2020, background): “While supporting the idea that singing itself might have a role in aerosol transmission, Hamner et al.(17) pointed out in a peer-reviewed report of the same outbreak that there were multiple opportunities for droplet and fomite transmission as choir members shared snacks and were in close proximity ”
- Coronavirus (COVID-19) (2020, background): “Although respiratory aerosol spread was initially controversial, a committee of the National Academy of Sciences has subsequently concluded there is some limited evidence that it is also spread by respiratory aerosols [27-35]; other evidence of aerosol spread is rapidly accruing, with increasing opi”
- Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients (2020, neutral): “For SARS-CoV-2, there have also been two 240 epidemiologic reports consistent with aerosol transmission.(15,34) However, despite these reports, 241 uncertainties remain about the relative importance of aerosol transmission of SARS-CoV-2, given that so 242 far, only one study has provided weak eviden”