Outbreak Associated with SARS-CoV-2 B.1.617.2 (Delta) Variants in an Elementary School — Marin County, California, May–June 2021

Details

• Personal Author:
  Lam-Hine, Tracy ; McCurdy, Stephen A. ; Santora, Lisa ; Duncan, Lael ; Corbett-Detig, Russell ; Kapusinszky, Beatrix ; Willis, Matthew
• Corporate Authors:
  Marin County Public Health. COVID-19 Case and Contact Investigation Unit. ; California. Department of Public Health. ; Chan Zuckerberg BioHub.
• Description:
  What is already known about this topic? The SARS-CoV-2 B.1.617.2 (Delta) Variants is highly transmissible. Prevention guidance in schools varies by jurisdiction.
  
  What is added by this report? During May 23–June 12, 2021, 26 laboratory-confirmed COVID-19 cases occurred among Marin County, California, elementary school students and their contacts following exposure to an unvaccinated infected teacher. The attack rate in one affected classroom was 50%; risk correlated with seating proximity to the teacher.
  
  What are the implications for public health practice? Vaccines are effective against the Delta Variants, but Transmission risk remains elevated among unvaccinated persons in schools. In addition to vaccination, strict adherence to multiple nonpharmaceutical Prevention strategies, including masking, are important to ensure safe school instruction.
  
  On May 25, 2021, the Marin County Department of Public Health (MCPH) was notified by an elementary school that on May 23, an unvaccinated teacher had reported receiving a positive test result for SARS-CoV-2, the Virus that causes COVID-19. The teacher reported becoming symptomatic on May 19, but continued to work for 2 days before receiving a test on May 21. On occasion during this time, the teacher read aloud unmasked to the class despite school requirements to mask while indoors. Beginning May 23, additional cases of COVID-19 were reported among other staff members, students, parents, and siblings connected to the school. To characterize the outbreak, on May 26, MCPH initiated case investigation and contact tracing that included whole genome sequencing (WGS) of available specimens. A total of 27 cases were identified, including that of the teacher. During May 23–26, among the teacher’s 24 students, 22 students, all ineligible for vaccination because of age, received tTesting for SARS-CoV-2; 12 received positive test results. The attack rate in the two rows seated closest to the teacher’s desk was 80% (eight of 10) and was 28% (four of 14) in the three back rows (Fisher’s exact test; p = 0.036). During May 24–June 1, six of 18 students in a separate grade at the school, all also too young for vaccination, received positive SARS-CoV-2 test results. Eight additional cases were also identified, all in parents and siblings of students in these two grades. Among these additional cases, three were in persons fully vaccinated in accordance with CDC recommendations (1). Among the 27 total cases, 22 (81%) persons reported symptoms; the most frequently reported symptoms were fever (41%), cough (33%), headache (26%), and sore throat (26%). WGS of all 18 available specimens identified the B.1.617.2 (Delta) Variants. Vaccines are effective against the Delta Variants (2), but risk of Transmission remains elevated among unvaccinated persons in schools without strict adherence to Prevention strategies. In addition to vaccination for eligible persons, strict adherence to nonpharmaceutical Prevention strategies, including masking, routine tTesting, facility ventilation, and staying home when symptomatic, are important to ensure safe in-person learning in schools (3).
  
  Suggested citation for this article: Lam-Hine T, McCurdy SA, Santora L, et al. Outbreak Associated with SARS-CoV-2 B.1.617.2 (Delta) Variant in an Elementary School — Marin County, California, May–June 2021. MMWR Morb Mortal Wkly Rep. ePub: 27 August 2021.
  
  mm7035e2.htm?s_cid=mm7035e2_w
  
  mm7035e2-H.pdf
  
  
• Subjects:
  Child CoronaVirus Infections COVID-19 Pandemics SARS-CoV-2 Schools Students
• Source:
  MMWR: Morbidity and Mortality Weekly Report 2021; v. 70 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:
  California
• Pages in Document:
  3 pdf pages
• Volume:
  70
• Collection(s):
  Morbidity and Mortality Weekly Report (MMWR)
• Main Document Checksum:
  urn:sha-512:f7d791faee3a1d55337e4094863c6d4383699806f688adaf48cb923e03bd16ce26b807afc9596b2a53165881dbe9a0461f6da4ed91f79b15cb0244e9ed99e13e
• Download URL:
  https://stacks.cdc.gov/view/cdc/109320/cdc_109320_DS1.pdf
• File Type:
  [PDF - 458.88 KB ]