A COVID-19 outbreak at a Marin County elementary school is a case study in how highly contagious the delta variant is.
The Centers for Disease Control and Prevention reported an unvaccinated teacher felt sick in May and assumed they had allergies. School policy required them to be masked, but the teacher removed their mask to read aloud, and within days, half of the 24 students tested positive.
The infection rate in the classroom's first two rows nearest the teacher was 80% -- eight of 10 students.
The sick students then infected siblings and parents for a total of 26 people stemming from a single case.
“It’s safe to say the index case was an unvaccinated person who was eligible to be vaccinated,” said Dr. Matt Willis, the county’s public health officer, to the Mercury News. “All the cases are unvaccinated individuals. That includes people who were eligible to be vaccinated but were unvaccinated and people who were not eligible to be vaccinated, by virtue of age.”
The CDC report doesn't name the elementary school in Marin County.
On Friday night, the San Francisco Archdiocese, which oversees Catholic schools in Marin County, released a statement that read in part: “The incident referred to in the CDC report was an isolated circumstance and has been addressed internally.”