Schools can safely reopen – epidemiologist describes what works and what doesn’t

Just as schools were preparing to reopen for the new school year, cases of COVID-19 began to increase in the United States, in large part due to the more contagious delta variant. School administrators across the country are working to get students back to class safely, while providing children with a nurturing learning environment.

As an infectious disease epidemiologist at the University of Washington, I spent a year and a half working with a group of epidemiologists and medical professionals to collect, review and assess the scientific evidence on COVID-19 for national and local public health agencies.

Our group concluded that vaccines and masking work well to prevent outbreaks of COVID-19 in schools, but other strategies like plexiglass barriers and temperature controls are probably not worth the effort.

What works

A COVID-19 vaccine is the most important tool to prevent COVID-19 in schools, as well as almost everywhere else. All vaccines currently licensed in the United States have been shown to help prevent infections and protect against moderate and severe illness. Some variants, such as delta, may be more likely to cause breakthrough infections, but vaccinations have shown protection against symptomatic illnesses caused by delta.

The more people who are vaccinated in a school, the lower the risk of an epidemic in the school and the lower the likelihood that a person will develop serious illness if infected. COVID-19 vaccines are currently available for anyone 12 years of age or older, and it is possible that at least one of the vaccines will be licensed for young school-aged children in the later months of 2021 or early 2022 .

Masks are also important. Not everyone in a school can or will choose to be vaccinated, and there is also a risk of major infections, especially the delta variant. Masks reduce the risk of an infected person spreading the virus and offer some protection to the wearer from infection. In the past school year, wearing a mask has been shown to reduce the spread of COVID-19 in schools. Masks also don’t disrupt the school day like other measures might, such as keeping students in fixed cohorts or reducing the school day for split shifts.

Which is probably not worth the effort

Other prevention measures have had limited effectiveness in some settings, but are probably not worth the cost and effort to implement in most schools.

Plexiglass barriers, common in businesses and other places, can be expensive and do little to prevent airborne transmission in school environments. In some situations, barriers such as desktop screens can actually increase the risk of transmission by reducing airflow.

Daily temperature checks and symptom screening have also not proven to be an effective way to prevent COVID-19 in public places. This approach misses asymptomatic cases, which are particularly common in children and young adults. Yet students, teachers and staff should stay home until they test negative if they are showing symptoms of COVID-19 or have been exposed to someone with COVID-19.

Other policies may reduce transmission but may disrupt students, such as a physical distance of at least 6 feet or separating students into cohorts that are not allowed to mingle. If students wear masks, and especially if most are vaccinated, these measures are unlikely to add much more protection. The CDC currently recommends 3-foot spacing in schools when possible and multi-layered prevention measures when this is not possible.

It’s probably not worth testing everyone on a regular basis. Frequent testing is expensive, and real-life examples and mathematical models indicate that routine asymptomatic testing for COVID-19 in schools offers little additional benefit beyond widespread vaccination and masking. However, the CDC includes some asymptomatic testing in schools as one of the potential components of a prevention strategy in childbirth.

What to do about lunch

When I talk to school administrators about Safe Reopening, one of the most common questions they ask me is how to organize lunchtime, when the students are together and can’t always wear masks. Many schools have included lunch over the past year without causing COVID-19 outbreaks, suggesting lunch can be done safely.

There is little direct evidence for the risk of transmission when comparing different approaches to the lunch problem, but there are a few basic guiding principles.

Students should wear masks when they are not actively eating. As difficult as managing a busy dining room is, yelling, singing, and talking loudly spreads more viruses and should be discouraged, especially without a mask. And good ventilation, especially in spaces where people eat, is important.

Students should also keep their distance from each other while eating. Schools may consider having more lunch times, feeding children in their classrooms, or using other spaces in the school to reduce clutter.

Risks outside of school

The most powerful driver of COVID-19 in children, teachers, and families isn’t school – it’s the level of community transmission.

Based on what we currently know, schools can continue to operate in person without widespread school-related transmission. When community transmission is high, schools should take extra precautions to stick to their prevention strategies. But the main way to protect students is to stop the spread of COVID-19 outside of school.

What we still don’t know

It is not known how the rise of the delta variant will affect the return to school. People infected with the delta tend to spread the virus more than those infected with other strains, and breakthrough infections of this variant can cause large outbreaks when other prevention measures are not in place. Relying only on vaccinations to control COVID-19 does not appear to be a winning strategy.

More and more children are infected during the wave of delta variants. There were sharp increases in July and August 2021 in the total number of children identified with infections and hospitalized for COVID-19. But the number of cases in the general population has also increased. There has been only a modest increase in the proportion of COVID-19 cases in children compared to other age groups, and this could be due to the fact that children represent a growing share of the unvaccinated.

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COVID-19 never fails to reserve new surprises. Many aspects of the next school year remain unknown, but by learning from what worked and what did not work in the last school year, we have evidence that in most situations, students can return to school safely in person as long as these multi-layered preventive measures are in place and followed.