School COVID Outbreaks Drop When Adults Wear Masks, Study Finds

WEDNESDAY, Dec. 22, 2021 (HealthDay News) -- Of course kids make up the bulk of people at schools, but new evidence shows that requiring masks for adults working at schools greatly reduces the severity of COVID-19 outbreaks.

In the study, the researchers found that children were most often the first identified cases in schools. However, outbreaks in schools were more severe when an adult was the first case, and mask wearing by adults significantly reduced secondary cases, according to the report published online Dec. 20 in Frontiers in Public Health.

"We can therefore recommend all-time mandatory masking in schools for both children and adults. In preschools, mask wearing could also reduce secondary cases," said study co-author Anika Kästner, of the University Medicine Greifswald, in Germany.

The closure of schools and preschools is widely used to try to prevent COVID-19 outbreaks, but doing so can put children at risk of social isolation, as well as learning and developmental setbacks. Other COVID preventive measures are key, experts say.

"To avoid school closures at high incidence levels, it is important to identify factors contributing to the spread of COVID-19 infections in schools and preschools," Kästner said in a journal news release.

The study team analyzed data on preschool and school outbreaks in Mecklenburg-Western Pomerania, Germany, between August 2020 and May 2021, when schools and preschools were: open in phase 1 (no mandatory masking); closed in phase 2 (lockdown in Germany); gradually opened in phase 3 (with mandatory mask use in schools); and in phase 4 (lockdown in Germany and only emergency care offered).

In schools, children were most often the first ("index") cases, but outbreaks were more severe when an adult was the first case. In phase 1, adult index cases caused on average nearly 5 secondary cases and children index cases caused on average 0.3 secondary cases. In phase 3, index adults caused 0.5 and children 0.3 secondary cases.

In preschools, where there was only a mask recommendation for adults, index adults caused on average 0.6 secondary cases in phase 1 and almost three secondary cases in phase 3. In both phase 1 and 3, children caused 0.5 secondary cases, according to the study.

"The reason for this difference between phases could be the increasing prevalence of the Delta variant, which causes more frequent infections in children," said study co-author Martina Sombetzki, of University Hospital Rostock.

The study had limitations. It did not account for the effects of vaccines and assumed that masking measures were fully implemented and followed in the schools.

Even so, the findings show that mask mandates, particularly for adults, were effective in reducing secondary cases, the study authors said.

More information

The U.S. Centers for Disease Control and Prevention offers a guide to masks.

SOURCE: Frontiers in Public Health, news release, Dec. 19, 2021