An unvaccinated elementary school teacher in California who was diagnosed with COVID-19 infected half of the students in their classroom and sparked a community-wide outbreak, according to a new report from the Centers for Disease Control and Prevention (CDC).
The teacher showed up to work while symptomatic and continued to teach for two days before receiving a test. She reported nasal congestion and fatigue, but attributed the symptoms to allergies.
The school required teachers and students to mask while indoors, but the teacher was reportedly unmasked when reading aloud to the class.
“This outbreak of COVID-19 that originated 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,” the report concluded.
Other than two teachers, one of whom was the index patient, all school staff members were vaccinated.
California has since put in place a requirement for every public school teacher to be vaccinated or get tested weekly, but the report also shows the shortcomings of the testing requirement.
The teacher became symptomatic on May 19, and received a positive test May 21. But the virus had already spread to the students, who began showing symptoms May 22.
Twelve of the teacher's 22 students subsequently received a positive test result, including eight out of 10 in the front two rows.
The report also found a separate outbreak at the same school, among unvaccinated students in a different grade. According to the CDC, six students tested positive. Investigators found that one student hosted a sleepover on May 21 with two classmates from the same grade. All three of these students experienced symptoms after the sleepover and tested positive.
The outbreaks in the separate grades were probably linked, the CDC said.
Cases were then identified in four different students from separate grades. These four students were siblings of students who were infected from the unmasked teacher, and exposure was assumed to have occurred in their respective homes.
In addition to the teacher and 22 infected students, four parents of students with cases were infected, for a total of 27 cases. Among the five infected adults, one parent and the teacher were unvaccinated; the others were fully vaccinated.
Aside from masks, all desks were separated by six feet. All classrooms had portable high-efficiency particulate air filters and doors and windows were left open.
CDC Director Rochelle WalenskyRochelle WalenskyFDA greenlights mix-and-match booster doses Fauci says trick-or-treating this Halloween ok Overnight Health Care — Presented by EMAA — Pfizer requests FDA authorize COVID-19 vaccine for 5 to 11 year olds MORE said the lesson should be that schools can be safe, as long as multiple layers of mitigation are followed.
"The introduction of the virus into the classroom by a teacher who worked in school while she was both symptomatic and unvaccinated and who was unmasked when reading aloud to a class resulted in cases within the classroom, across the school, and among families of students and staff in the community," Walensky said during a press briefing.
"We know how to protect our kids in school. We have the tools."
Until children under age 12 are eligible to be vaccinated, the CDC says the best way to keep them safe in schools is to use all the tools available, including physical distancing, masks, ventilation and vaccines for everyone else who is eligible.