Since fall 2020, I have served as a medical and public health consultant for a private K-12 school system in the Washington, DC area. At that time, many schools were trying to figure out how to safely reopen for in-person instruction after having taught students online after the COVID-19 pandemic began with unacceptable results. With vaccines for adults and children still in development, schools were implementing a variety of interventions in the hope that some would mitigate viral spread: spacing students six feet apart, universal masking, temperature and symptom screening, regular testing, frequent sanitizing, improving ventilation, hybrid scheduling, cohorting, and quarantines. New studies appeared constantly, and it was my job to sift through the imperfect data to advise the best course of action in the context of changing community infection rates and parents who either felt that the school system wasn't doing enough to protect their children or was doing "too much" and unnecessarily restricting classroom or extracurricular activities.
When effective and safe vaccines became available, first for adults, then adolescents, then for children aged 5 or older, we strongly encouraged everyone to receive them, and I personally hosted virtual and in-person question and answer sessions for employees. The schools I advised required that students and staff wear masks until February 2022, after the vast majority had been vaccinated and boosted, if eligible. Given the increasing frequency of (mostly mild) infections in vaccinated persons and continued skepticism about the value of masks in preventing viral spread, though, I have continued to keep up with the literature on these topics. Two recent large observational studies are worth highlighting.
During the 2021-22 school year, schools could require that everyone wear masks (universal masking), that some grades wear masks or that masks be required at a community infection threshold (partial masking), or make masks optional. A study of more than 1 million students and 150,000 staff across 61 school districts in 9 states found a clear benefit of universal compared to optional masking: "Districts that optionally masked throughout the study period had 3.6 times the rate of secondary transmission as universally masked districts; and for every 100 community-acquired cases, universally masked districts had 7.3 predicted secondary infections, whereas optionally masked districts had 26.4." This finding was consistent with a prior study that compared COVID-19 incidence in school districts in Arkansas during the tail end of the delta wave (August-October 2021) and found that "districts with universal mask requirements had a 23% lower incidence of COVID-19 among staff members and students compared with districts without mask requirements."
Masks are not perfect, and some types of masks work better than others. But they do work!
An online survey of more than 1 million respondents living with school-aged children in all 50 states and Washington, DC examined the COVID-19 risk associated with in-person schooling during spring 2021, when most adults were vaccine-eligible but most students were not. By June, about 75% of respondents had received at least one COVID-19 vaccine dose, a slightly higher proportion than the general population at that time. As expected, living in a household with a child in full-time in-person schooling was associated with an increased odds of experiencing COVID-19-like illness (adjusted odds ratio, 1.32). However, as the number of school-based mitigation measures increased, the risk decreased: "By May to June, risks of all COVID-19 related outcomes disappeared when four or more mitigation measures were reported." Among more than 116,000 teachers included in the survey, those who taught students in person had a higher risk of testing positive (aOR, 2.04) and losing one's taste or smell (aOR, 1.37). However, being vaccinated lowered this risk, to the point where "vaccinated teachers working outside the home were less likely to report COVID-19-related outcomes than unvaccinated teachers reporting no work outside the home."
Vaccines are not perfect, and they are more protective against some viral variants than others. But they do work!
We have reached the point where reinstituting community mask mandates is politically impossible in most parts of the U.S. and mandatory vaccination policies have limited by the courts to employees of the federal government (including active military) and health care organizations. Closing schools and businesses early in the pandemic did buy time to develop vaccines and antiviral drugs, but the societal and economic costs were devastating. By comparison, masks are uncomfortable and vaccines have rare adverse effects that are many orders of magnitude lower than the risks associated with COVID-19. Keeping schools open without facilitating community transmission will continue to remain a challenge as variants continue to evolve. It's been a humbling experience for me, as it has been for all professionals doing our best to protect the public's health.