High SARS-CoV-2 Attack Rate Following Exposure at a Choir Practice — Skagit County, Washington, March 2020

Details

• Personal Author:
  Hamner, Lea ; Dubbel, Polly ; Capron, Ian ; Ross, Andy ; Jordan, Amber ; Lee, Jaxon ; Lynn, Joanne ; Ball, Amelia ; Narwal, Simranjit ; Russell, Sam ; Patrick, Dale ; Leibrand, Howard
• Corporate Authors:
  Washington (State) Department of Health. ; Skagit County (Wash.). Health Department.
• Description:
  What is already known about this topic? Superspreading events involving SARS-CoV-2, the Virus that causes COVID-19, have been reported.
  
  What is added by this report? Following a 2.5-hour choir practice attended by 61 persons, including a symptomatic index patient, 32 confirmed and 20 probable secondary COVID-19 cases occurred (attack rate = 53.3% to 86.7%); three patients were hospitalized, and two died. Transmission was likely facilitated by close proximity (within 6 feet) during practice and augmented by the act of singing.
  
  What are the implications for public health practice? The potential for superspreader events underscores the importance of physical distancing, including avoiding gathering in large groups, to control spread of COVID-19. Enhancing community awareness can encourage symptomatic persons and contacts of ill persons to isolate or self-quarantine to prevent ongoing Transmission.
  
  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.
  
  Suggested citation for this article: Hamner L, Dubbel P, Capron I, et al. High SARS-CoV-2 Attack Rate Following Exposure at a Choir Practice — Skagit County, Washington, March 2020. MMWR Morb Mortal Wkly Rep. ePub: 12 May 2020. DOI: http://dx.doi.org/10.15585/mmwr.mm6919e6
  
  mm6919e6-H.pdf
  
  
• Subjects:
  CoronaVirus Infections COVID-19 Music Singing
• Source:
  MMWR: Morbidity and Mortality Weekly Report 2020; v. 69 Early Release
• Series:
  Weekly Report: Morbidity and Mortality Weekly Report (MMWR)
• ISSN:
  0149-2195 (print) ; 1545-861X (digital)
• Document Type:
  Journal Article
• Place as Subject:
  Washington
• Pages in Document:
  5 pdf pages
• Volume:
  69
• Collection(s):
  Morbidity and Mortality Weekly Report (MMWR)
• Main Document Checksum:
  urn:sha-512:e58b64e7e7b3de0ccc71a703ecdd364aed69e0aad8202416301f414ca32d113e1ae1eecae5867d1b37f697b9bb8d265fa6e838aaffa6db237a97d6cdf962ea20
• Download URL:
  https://stacks.cdc.gov/view/cdc/87883/cdc_87883_DS1.pdf
• File Type:
  [PDF - 233.14 KB ]