While relatively few schools experienced widescale outbreaks during the pandemic, the return to full-time, in-person instruction will inevitably increase students’ exposure to the coronavirus.
But the number and kind of protections schools put in place now can make a big difference in the risk that those students will bring the illness home to family members, according to a study published last month in the journal Science. Even as more adults and older students become vaccinated, the study suggests no one safety measure will be a silver bullet when it comes to preventing COVID-19.
“When we talk about the risks from in-person schooling, our tendency is to think about it in terms of risk of transmission in the classroom,” said Justin Lessler, the lead author of the study and an associate professor of epidemiology at Johns Hopkins Bloomberg School of Public Health. “But really there are a whole host of activities that go along with in-person schooling, including the transport to and from school. All of the ancillary activities can have as much impact on transmission as what’s going on in the classroom. So when we think about school, we should be thinking about the whole picture.”
President Joe Biden and more than a half-dozen state leaders have pledged that all schools will return to full-time, in-person instruction by next school year. Yet evidence is building that reopening classrooms could increase the risk of COVID-19 to individual students’ families. One recent RAND study found families of schoolchildren attending in person had a 3 percent higher rate of illness per 10,000 cases, while a separate University of Kentucky study linked 12 percent of Texas COVID-19 cases and 17 percent of deaths during the two months of the study to the timing of schools reopening in the state.
The Science study also found significant risk for families of children who returned to in-person instruction. After adjusting for county-level spread of the virus and other county- and individual- background factors, the researchers found that living in a household with a child who attended school in-person full time was associated with 1.38 higher odds of developing COVID-like symptoms (such as a fever with shortness of breath, coughing, or difficulty breathing); 1.21 higher odds of losing their sense of taste or smell (another symptom associated with COVID-19); and 1.3 higher odds of having a positive test for SARS-COV-2, the virus that causes COVID-19.
And the link between living with a child attending in-person school and COVID-19 was strongest at older grade levels, and was smaller but still significant for families of children who attended school in person part time, rather than full time.
“The biggest surprise was just the sheer magnitude of the impacts. Remember, we’re not looking at an increase in risk among the children themselves here; we’re looking at the increase of risk of the family members,” Lessler said. “Seeing a 20 [percent] or 30 percent increase in the odds of reporting outcomes associated with COVID among family members of kids, is a scope that is, I think, bigger than we expected going into it.”
The researchers surveyed data from more than 600,000 families across the country whose children attended 130,000 schools using different strategies to prevent the spread of the coronavirus which causes COVID-19, including:
- teacher masking,
- student masking,
- daily symptom screenings,
- restricting the entry to school,
- creating extra space among students and staff, preventing people from sharing supplies,
- keeping the same students together in cohorts,
- reducing class sizes,
- ensuring students have the same teacher throughout the day,
- closing the cafeteria,
- closing the playground
- barring in-person extracurricular activities
- using physical desk shields or separators,
- holding classes outside, and
- having students attend part-time.
Because the study surveyed families on the mitigation measures at their schools, it did not include some major infrastructure measures, such as installing new heating, ventilation, and air conditioning systems to increase indoor air quality or changing building-level sanitation protocols.
The researchers found no single mitigation strategy eliminated the risk of moving to in-person schooling, but families whose children attended schools that collectively implemented seven or more strategies had no greater risk of illness than families whose students did not attend school in person.
And some strategies did seem more beneficial than others. Daily symptom screenings for those coming onto campus (with those found to be sick staying home), teacher masking, and stopping extracurricular activities were associated with the biggest drops in the risk of family members developing COVID-like symptoms or having a positive COVID-19 test. By contrast, closing playgrounds seemed to have no effect, and using physical desk shields to separate students in the classroom was associated with a higher risk of later illness among family members.
“The teachers I’ve talked to have stressed that desk shields can really have pretty big impacts on how they interact with students; like, if you have to interact with students around that barrier, you might go closer, there could be other behavior changes” that might raise infection risk, Lessler said.
He also noted that the physical barriers could change the air flow in a classroom in ways that keep viral particles in the air longer. However, he said the study did not find any evidence that would conclusively point to why desk shields had the effect they did, and noted that because fewer schools overall used the desk shields without also using many other interventions, their effectiveness would need to be tested separately.
Community, staff vaccinations remain key
While the study found teachers’ risk of contracting COVID-19 or having COVID-like symptoms rose when they moved from virtual to in-person instruction, their risk rose no more than it did for those in other professions, such as health-care and office workers.
That risk declines even more, of course, for teachers who are fully vaccinated against the virus. By the latest federal estimates in March, a third of schools with an 8th grade and nearly that many schools including a 4th grade had given 60 percent or more of their teachers at least one dose of COVID-19 vaccine. In many communities, teachers have been vaccinated faster than the general population.
“What is needed will depend a lot on how much disease there’s out there in the community,” Lessler said. “I think vaccination is going to bring cases way, way down by the fall, but … no one wants to bring COVID home to a grandparent who maybe wasn’t successfully vaccinated. There may be reason to consider some mitigation measures in place perhaps permanently.”
For example, while schools likely will eventually bring back extracurricular activities, he said, contact tracing and daily symptom checks may be worth keeping even after the pandemic is fully under control.
“Even if it’s not COVID, even if it’s the flu, you could argue that that it’s something important a school should be considering doing in the future,” he said.