When state officials were deciding whether to shutter their schools back in March, the evidence they had to work with was thin. They knew kids easily catch and spread influenza — and that school holidays and closures have helped slow its spread. But they weren’t sure if the same was true for Covid-19.

Now, a study published Wednesday in the Journal of the American Medical Association shows that closing all of a state’s schools was associated with a drastic decrease in both Covid-19 cases and deaths. And the point at which officials made that call mattered: Those states that adopted the policy while few people were testing positive saw a correlated flatter curve of cases.

“It’s a nice study. It’s clear that coincident with closing down schools, the numbers improved,” said Helen Boucher, chief of the division of geographic medicine and infectious diseases at Tufts Medical Center, who wasn’t involved in the research. But she noted that we have to be careful about drawing overly broad conclusions from a single sliver of a sweeping shutdown strategy: “School closing didn’t happen in a vacuum.”

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It also still isn’t clear how likely kids of different ages are to get and pass on the virus, which makes it hard to tease out the reasons why school closures might have helped to shift the outbreak.

“It’s quite possible — and probable — that people changed their behavior because they thought, ‘Oh my goodness, there’s this new virus and it’s so scary they’re closing schools,’” said pediatrician Katherine Auger, associate chair of outcomes at Cincinnati Children’s Hospital Medical Center, and the first author of the new paper.

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“One thing we can’t tease out is how much of the effect was related to the virus spreading within schools, and the larger change in the community because now parents aren’t going to work,” she added.

The findings arrive amid a furor over school reopenings. This spring, the Centers for Disease Control and Prevention released guidelines about preventing viral transmission within schools, recommending that students be physically distanced, by placing desks 6 feet apart, for instance. For some schools, that seemed impossible, given the number of kids enrolled and the architecture of classrooms. That meant that at least some teaching would take place online, which contradicted the president’s rosy — and to many public health experts, risky — ideas about reopening.

After both Trump and Vice President Mike Pence criticized the guidelines and encouraged schools to reopen fully, the CDC released revised guidelines, which sparked fears that federal public health experts were caving under political pressure.

The new study doesn’t show cause and effect, only an association between school closures and case counts in an area. The authors warned it also can’t provide a blanket prescription for the fall.

“Our study took place at a time when schools weren’t doing things like masking,” Auger explained. “It’s really impossible to project the old way of schools into the future of schools, assuming they’ll be following the expert guidelines.”

To her, the work supports the “flexible and nimble” approach backed by the American Academy of Pediatrics. Having kids physically present in schools doesn’t just spur academic learning and the essential cognitive and emotional development that comes from social interaction, the organization stated. It also allows them to receive a slew of services, from free meals to adult eyes that might pick up signs of abuse at home.

But those benefits have to be weighed against the risks of Covid-19 for kids, parents, grandparents, and teachers — a threat best kept in check with rapid testing that much of the country cannot provide.

In the new study, Auger and her team compared reality — in which all 50 states closed schools in March — to a computer model in which everything else stayed the same while schools remained open. They calculated the time it would’ve taken for infections acquired in schools to be transmitted, and for those patients to then show up in hospitals and for a certain fraction of them to die.

Their projection found that, if schools had stayed open, there could have been roughly 424 more coronavirus infections and 13 more deaths per 100,000 residents over the course of 26 days.

Extrapolate that to the American population, and the country might have seen as many as 1.37 million more cases and 40,600 more deaths, explained Samir Shah, the director of hospital medicine at Cincinnati Children’s Hospital Medical Center and one of the authors of the paper.

“These numbers seem ridiculously high and it’s mind-boggling to think that these numbers are only … in the first several weeks,” said Shah. “That’s bonkers.” He warned, though, that those numbers should be taken with a grain of salt. While their statistical model attempts to pinpoint the impact of schools staying open or being closed, the method can’t actually establish any sort of causal relationship.

The authors realized that their estimation of how long it might take an infection picked up in a school to turn into a symptomatic case of Covid-19 might be off, and wondered if that might influence their results. When they changed those time lags, though, they still found a significant correlation between closing schools and decreased caseload and mortality.

To Steffanie Strathdee, associate dean of global health at University of California, San Diego, that was what made this study convincing. “This study was taking imperfect data but doing a very elegant analysis,” she said. “If we were wrong, what’s the other extreme, would it change the results? If these kids infected parents, but it took a little longer or a little shorter, what then?”

The bottom line, she said, was that strategies such as school closures do seem to make a difference when it comes to the risks of Covid-19.

Auger’s team also analyzed whether the timing of school closures was correlated to a change in cases and deaths. “States who closed schools before their Covid numbers were high had the largest effect,” she said.

While kids seem to be less likely to get sick than adults, there is some evidence that schools can be important sites of coronavirus transmission. Younger children appear less likely to pass on the virus than tweens and teens, though more research is needed to fully understand the various risks.

Shah, meanwhile, warned that people reading the study should not forget about the risks of interruptions to schooling. “We can quantify the risk of Covid. It’s much harder to quantify the risk of being absent from school for a prolonged period of time,” he said.

Both he and Auger emphasized the importance of tailoring strategies to the needs and coronavirus risks within each family and community, and that better, quicker testing would allow for a safer back-to-school strategy. “It’s a real challenge, and I think that our study is one very important piece of the puzzle in how we think about this,” Shah said.

  • I am so disappointed that you would report a study as to children and closing schools as reducing Covid in the unscientific manner that you did. Reading your headlines, it sounds like closing schools reduced Covid. Instead, when you read the study, you see that closing schools was just one of the many things done (including having everyone stay at home) before scientists realized that children 12 and under don’t have the same ACE receptors to allow Covid into their cells and are so much less likely to get infected. Your article sounds like it was sponsored by the teachers union that is putting the fear of teachers above science and the interest of children in returning to school, including the number of children, e.g. in the Bronx who have no access to Wi-Fi or computers.

    Your article appears to be so tied into the “study” published by the NY Times that “shows” that children may carry the same amount of virus as adults – when you look at the study, the adults carry an average of 11-17, and the “highest level” of children (which it doesn’t say whether this is only one child) can carry 12, even though the study showed that children overall carry much less.

    Can you please be sensitive as to how your headlines will be used and be more factual rather than allow your headlines to be used by special interest groups who have an agenda?

    Thank you.

  • Would really like to see the “researchers” explain how there’s such a spike everywhere this summer with the vast majority of schools CLOSED but restaurants and bars open?? But sure it was the SCHOOLS that kept the virus low! What a useless load of trash “research” with a very very clear POLITICAL agenda. Also how do you explain the lower counts in states like Montana which did allow schools to open? Or South Dakota and Iowa-while closing schools didn’t have hard and fast SIP orders?

    • Can’t agree more, Monyka. It is a slow but direct march into whitewashing this entire country getting ready to apply one giant single color of nothing.

  • Comments quoted in this article and many others I have read express concern over the “trauma” children will face due to not being able to be present in school with their teachers, with their fellow students, with direct teaching, wth school and other services. I understand most of this concern, but I don’t see commentary on how much of this might be mitigated by distant learning, plus an addition of distant socializing facilitated via Zoom that includes fellow students, plus online tutoring, plus delivery of meals, plus the lack of bullying and other negative social pressures that are typically present within the school environment in the form of “gangs” or cliques.

    Also, while a “school” may, as an institution, intend to follow all the appropriate rules and guidelines meant to minimize risks of infection, this does not at all assure that the students will all always follow these same rules and guidelines. Monitoring and managing the students will be a huge job that will, in practice, require additional adult eyes, ears and intervention. Imagine a new “game” or form of torture that involves pulling a fellow student’s mask off, for one example of a new way to bully.

    Imagine, also, the fear that many students will experience just from everyone wearing masks and being monitored and disciplined for breaking the rules because someone might get sick and possibly die. Or that someone at home might get sick and possibly die because the student brought the virus home. What will the punishments be for infractions of the rules? What trauma might result from this whole new level of shame and guilt?

    Also, to make schools safer, students will need to be spread out more, quite likely requiring splitting classes and needing more rooms (if there are any) with additional staff, all of whom will need training for dealing with this new situation. And all of this will require more funding which is already in short supply. More cleaning and sanitizing will probably require more custodial staff – more training, more money. All with uncertain results and possible (likely) breakdown resulting in illness and death. Putting many breathing, talking, sneezing, coughing bodies together for long periods of time in an enclosed space with a less than adequate ventilation system is asking for trouble. Sitting six feet apart or even ten feet, is hopelessly inadequate – everyone will be breathing the same air with the same germs because it will be physically unavoidable.

    When some people, even Dr. Fauci, say that having children in school will help us learn a lot about the virus that we don’t yet know, consider that this translates into them saying that students in school will make great guinea pigs for a huge experiment to learn more aout the virus. In other words, we will learn a lot from students and staff, as well as families and others in the communities, getting sick and dying. Is this about students learning or about scientists and society learning at the expense of the students and the many others associated with them?

    In this new study in Korea, it was shown that Covid-19 transmission within households was highest if the index patient (the initial contact person with Covid-19) was a child of age 10–19. This means that children ages 10–19 transmit Covid-10 very effectively – as effectively as adults. Children younger than 10 years old were around half as likely as adults to spread the virus. This suggests that it is unwise to send children to school during this Covid-19 pandemic.
    Contact Tracing during Coronavirus Disease Outbreak, South Korea, 2020
    https://wwwnc.cdc.gov/eid/article/26/10/20-1315_article

    • Yes Carl we get you hate the idea of schools open. No matter the abuse that may happen at home, ignore the fact that the poorer or more rural districts do not have money nor equipment for distance learning, ignore the fact that most parents cannot both work and teach, ignore the fact that we’ve had essential workers out there this entire time so you can continue to get your McD hamburger and starbucks coffee daily but now teachers need hazard pay.

    • Thank you for this reply. It is succinct and thoughtful, and while I thought I had considered every facet, I hadn’t.

      I have donated to meal delivery groups in my district, our schools have kept food coming. I am working with groups to provide tutoring for at risk kids while they are home. There is a lot a community can do to help, while keeping our teachers and children safe.

      Abuse has worried me. I am fairly certain someone I know is hurting their child, and there is no mandated reporter in the form of a teacher to talk to. So I might be punting, which is truly terrible. Communities can help abused children (it’s not always hidden very well) but we always expect “someone else” to do it. Usually a teacher.

      The bullying aspect was a new one to consider for me, especially the “pull down the mask” concept. As a parent of a middle schooler, yes.

      I know parents need to get back to work. Boy do I know.

      But these issues are not 1D; they are complex, multi-faceted knots that need to be worked out and considered from the scientific, sociological, and yes, even economic impacts.

      Thank you for this article and the reply.

  • Whatever this report seems to theorize, I guess we’ll find out soon enough as states seem to be jumping head first into the shallow pool. My personal prediction, a cow puck show like we’ve never seen before as this pandemic hits overdrive. My take, no viable vaccine, no immunity and a slow burn for years, much like the flu on steroids with no alternatives covering this worst case scenario.

    • You are a pessimistic one aren’t you.

      T-cell immunity. Look into this, and the data that shows children rarely get sick from, or transmit, coronavirus

  • This is one of the worst pieces of click bait science reporting I’ve seen since this all started. “School closures in spring linked to drastic decrease in Covid-19 cases and deaths” did the person writing the headline even read the article? It’s reporting like this that is responsible for the amount of misinformation, mistrust, and confusion regarding the science of Covid. Extremely disappointing from a site I have previously found pretty responsible.

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