What Does Science Say About Masks In School? (It Says Wear Them)

There are many headlines these days about the controversies surrounding re-opening schools with mask mandates. Some states are taking a surprising turn to ban mask mandates, leaving mask wearing up to parents. Most states are following the guidance from the Centers for Disease Control (CDC) and the Academy of American Pediatrics (AAP) and requiring students and staff to wear masks in school. This kind of "controversy" can make us doubt our information sources and question who we can trust. In today's post, we'll look at what the science says. (Spoiler: It says kids should wear masks in school.)

About 15 years ago, a group tasked with creating a national pandemic response plan under President George W. Bush considered all the options our country had when responding to a highly infectious disease spreading quickly through the nation. The conventional tools for response were limited to two actions: Isolation and vaccination. Make sure infected individuals were kept apart from the general population and work as fast as possible on a vaccine. These are two essential steps, but models indicated they alone would not be enough to help mitigate the spread of the disease, especially a disease like COVID-19 that has many asymptomatic carriers as well as a long incubation period. This team used these advanced computer-assisted modeling to identify non-pharmaceutical interventions that could help flatten the curve to a point where fewer people were infected in the first place. Their models indicated one significant factor to slow the spread of a disease was the closing of schools. Due to their plan, the country closed schools down for almost an entire school year, a decision that may have helped prevent millions of cases and hundreds of thousands of deaths.

But what about now? As schools are preparing to open for the new year, do we really still need to have students and staff in masks? Let's look at the science.

Is SARS-CoV-2 still spreading?

Yes. In many areas of the country, the rates of infection are as high as they have ever been, and in some areas, higher than during the peak of 2020. Most of the new cases are among unvaccinated individuals. The delta variant, a highly contagious strain of SARS-CoV-2, is responsible for 86% of new infections. Hospitalization rates are also an important metric. Even the most conservative voices discussing mask wearing in schools say that we should wait until hospitalization rates fall below 5:100,000 before removing mask mandates. To put that number in context, hospitalization rates in Florida are 42:100,000 and in Texas, 24:100,000.

Do masks help slow the spread of SARS-CoV-2 in schools?

Yes. There are two main studies to consider. The first included over 90,000 students and staff and examined in-school transmission of COVID-19 in North Carolina. They found 773 positive cases which led to an additional 32 cases due to in-school transmission. In most of the in-school cases, the cause of the infection could be traced back to lack of mask use or improper mask use. Combined with other studies of in-school transmission from Wisconsin, Georgia, Utah, Indiana, and New York, this resulted in an attack rate (number of new cases during a set time interval) of .5-.7% for positive cases in schools where mask mandates are in place and followed. (This last part is important: Just having the mask mandate does not result in slower spread of disease; the schools have to comply with the mask mandate for there to be an impact.)

The second study is far smaller, but unique in that it included a school where there was community spread of COVID-19 and a school with relaxed mask mandates (it is difficult to find schools without masks during the peak spread of the virus). In this unique setting, a large school relaxed mask wearing due to a heat wave. During the period of the study, 2 infections led to 178 in-school transmissions. This school's data, as well as some other small studies, combine to indicate that the attack rate of schools with community spread of COVID-19 is between 13.2% and 16.6%.

Another way to look at the impact of masks on in-school transmission of COVID-19 is to look at settings where children congregate in a way similar to school, but without wearing masks: Summer camps. A quick Google search will reveal hundreds of stories of COVID-19 outbreaks at summer camps where children and staff were not required to wear masks. Affected camps include outdoor camps, indoor camps, day camps as well as sleep-away camps. Where there were outbreaks, there were no masks. In contrast, of the hundreds of camps run by the YMCA under nationally-mandated mask wearing requirements, there were no such outbreaks. 

We'll end this post with a summary which can be found throughout the literature about wearing masks in schools during the COVID-19 pandemic: Where mask mandates are followed, there is little to no in-school transmission of COVID-19. Masks work, even without social distancing! Along with getting more and more Americans vaccinated, it's the best thing we can all do for ourselves and for each other.