Masking in schools

Amid the cultural conversations surrounding COVID-19, a new flash point has emerged of how to best protect children attending school in person. What precautions should schools take? And should children wear masks?

Several studies have found that schools with mask mandates have a lower rate of COVID-19 transmission among students. Yet was it the masking that reduced transmission, or were those schools also more inclined to use other measures to prevent the virus’s spread? Those could include improving ventilation, asking teachers to wear masks, social distancing, and hand-washing. The studies found a combination of factors effective, but didn’t prove each individual intervention worked.

One CDC study on Georgia’s schools in the last two months of 2020 does just that, according to New York magazine’s Intelligencer blog. The Georgia study enrolled more than 91,000 students in school districts that varied widely, both in geography and in measures taken against COVID-19. Then the researchers considered statistics about each possible intervention. The study’s timing in late 2020 means it missed the effects of widespread vaccination and the delta variant, but it still gives us a useful snapshot of what did and didn’t work.

Broadly, we can think of three categories of interventions: those that clearly help, those that clearly don’t, and the ones researchers are still unsure about. First, the uncontroversial part. As WORLD reported last year, ventilation remains a powerful tool with well-proven benefits. Since the virus spreads through the air, schools—and other venues where people meet inside—can reduce the danger of COVID-19 by improving air quality. Nor is the difference a small one: Even free or cheap changes like opening windows and adding fans cut transmission by 35 percent, whereas filtering air in closed rooms cut it by 31 percent. Schools that filtered air and also boosted airflow slashed transmission almost by a half.

Given that people with COVID-19 transmit the disease through the air, interventions that didn’t change who was breathing the air didn’t do much. Hand-washing helped a little, decreasing transmission by 12 percent. Adding physical barriers without improving ventilation accomplished almost nothing, and moving desks 6 feet apart likewise showed essentially no benefit.

Do masks fall into the former or the latter group? Perhaps inevitably, the Georgia study serves as a Rorschach test: Mask opponents will note that the study “fails to reach statistical significance.” (Reaching statistical significance refers to establishing that one’s finding had under a 5 percent likelihood of being due to random chance.) Mask advocates will note that it comes close, and that the study did prove a benefit for masks for teachers and staff, who likely wear their masks more properly than children often do.

Duke University’s ABC Science Collaborative released its own guidance in June, and the disconnect between its recommendations and the CDC’s newer findings demonstrates just how little we knew. The Duke team emphasized hand-washing—which we now know doesn’t help much—but placed little importance on ventilation—which does. It also placed a high value on masks for students, arguing that “in the absence of masking, ventilation may become more important but should not be considered a substitute for masking.” Yet the CDC does not see the two as conflicting, as the study proved a benefit for ventilation while only suggesting one for masks.

The Duke team also emphasized vaccines as a way to prevent both severe disease and COVID-19 transmission. The former remains true: Vaccination against COVID-19 has saved countless lives and continues to offer strong protection against dying or being hospitalized with COVID-19. But the delta variant changed how we think about transmission, with the virus now spreading even via vaccinated people (albeit at a much lower rate).

The CDC report suggests that masks for students do likely help. Yet it doesn’t prove it, and where schools or parents choose otherwise, ventilation along with vaccines and masking for teachers still limits COVID-19’s impact.