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Study: Vaccination and masking remain crucial in school environments

A new study released Aug. 27, 2021, by Centers for Disease Control and Prevention (CDC) and authored by Berkeley Public Health DrPH candidate Tracy Lam-Hine, investigates a COVID-19 outbreak in a Marin County elementary school classroom in May-June 2021. Lam-Hine also works as an epidemiologist for the County of Marin Department of Health and Human Services.

The outbreak originated with an unvaccinated teacher who occasionally unmasked while working in the classroom for two days after developing symptomatic COVID-19, but before receiving a positive diagnosis. A total of 27 cases tied to the symptomatic teacher were eventually identified. The specimens indicated the Delta variant of SARS-CoV-2, the virus that causes COVID-19.

Within five days after the teacher’s positive diagnosis, 22 of 24 students in the classroom, all ineligible for vaccination because of age, were tested for SARS-CoV-2; 12 tested positive. The risk of testing positive was correlated with being seated nearest the teacher.

The outbreak, originating with an unvaccinated teacher, highlights the importance of vaccinating school staff members who are in close indoor contact with children ineligible for vaccination as schools reopen, as well as strict adherence to other non-pharmaceutical prevention strategies such as wearing masks properly at all times while indoors, routine testing, ventilation, and staying home when symptomatic.