Hot Topics in Infection Prevention: Unvaccinated Teachers Infect Unvaccinated Children, New South African Variant

The outbreak underscores the Delta variant’s potential for rapid spread especially in schoolchildren who are too young to be vaccinated.

Unvaccinated Teachers Make Children Vulnerable to COVID-19

Schools are gearing up and recent publications from the Center for Disease Control and Prevention (CDC)’s Morbidity and Mortality Weekly Report (MMWR) are shedding insight into transmission within school settings. In one cluster within Marin County, California among elementary school students and their contacts, researchers learned the exposure was due to an unvaccinated infected teacher. The attack rate within the classroom was 50%. Despite high rates of masking and distancing guidance within the school, “the teacher was reportedly unmasked on

occasions when reading aloud in class.” While this cluster demonstrated the efficacy of vaccines in COVID mitigation, the researchers emphasized that “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 outbreak’s attack rate highlights the Delta variant’s increased transmissibility and potential for rapid spread, especially in unvaccinated populations such as schoolchildren too young for vaccination. However, transmission to community contacts appeared lower than that of some previously reported Delta variant outbreaks. Further transmission might have been prevented by high levels of community vaccination; at the time of this outbreak, approximately 72% of eligible persons in the city where the school is located were fully vaccinated.” This was followed by another MMWR on transmission rates in a K–12 school in Los Angeles, California. In this case, the research team assessed 463 school-associated cases from September 1, 2020–March 31, 202, noting that “the level of protection appears to be higher in children and adolescents than in adults, which is promising for children aged <12 years because no COVID-19 vaccine is currently authorized for this age group. In schools with safety protocols in place for prevention and containment, case rates in children and adolescents were 3.4 times lower during the winter peak compared with rates in the community. This analysis reflects transmission patterns before the more transmissible SARS-CoV-2 B.1.617.2 (Delta) variant became predominant in the United States.”

New South African May Be Highly Transmissible

These findings are particularly important as half of U.S. 12–17 year-olds have received their first dose of the COVID-19 vaccine. This will be increasingly necessary as schools go back into session and growing concerns of Delta amplifying transmission in these settings. A new variant identified in South Africa, C.1.2., is also sparking much conversation about transmissibility and mutations. Identified in May, C.1.2. has now been found across 6 of the 9 South African provinces. While a more transmissible variant isn’t entirely unexpected (ahem Delta), it’s important to take a measured approach about what we’re actually seeing for C.1.2. as these findings were based off a single paper. Per the authors “The mutations on the virus ‘are associated with increased transmissibility’ and an increased ability to evade antibodies, the scientists said. ‘It is important to highlight this lineage given its concerning constellation of mutations’.” More information will surely be coming regarding this new variant, but in the meantime, it reinforces the importance of global vaccine distribution and non-pharmaceutical interventions (NPIs) that are an effective and complementary tool.