07 Sep 2021

Weekly COVID-19 Update – The Marin County School Outbreak – Episode 77


Elementary School COVID19 Breakout and What it Teaches Us

 

A recent report, published on the CDC Morbidity and Mortality Weekly Report (MMWR) website: Outbreak Associated with SARS-CoV-2 B.1.617.2 (Delta) Variant in an Elementary School — Marin County, California, May–June 2021

https://www.cdc.gov/mmwr/volumes/70/wr/mm7035e2.htm

Detailed an outbreak of COVID19 that took place in May of this year in Marin County. At the time the school and region were following the current guidelines with schools open and in-person but masks were required while indoors.

An index case from an unvaccinated teacher who unmasked intermittently while teaching students, who according to the report, had good compliance with the masking policy infected a total of 27 cases that they were able to track down. The likely number was much higher but they were unable to track, trace and test all of the subsequent contacts. Further Phylogenetic tree classification of other individuals tested later showed identical versions of the virus suggesting this infection had a wider impact beyond the 27 detailed in the report

Notably, 6 were infected from a separate grade room and 8 additional cases of parents and siblings were infected of which 3 were fully vaccinated.

We don’t know the precise age or grade, but they fall in the kindergarten to Grade 8 range and all <16 and at the time ineligible for vaccination which at the time CDC recommendation was for vaccines for those 16 and up.

The team confirmed these cases were caused by the Delta variant by sequencing the virus from each of the individuals that had been identified as positive. At the time, the Delta variant was still emerging but had not reached the levels we are seeing now

What can we learn from this detailed study of an outbreak?

🙏No blame reporting is essential to improving our understanding and science

➡️The unvaccinated are at increased risk of getting COVID19 even more so with the Delta Variant

❗️The unvaccinated increase the risk of infecting others

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