do schools spread covid

Do Schools Spread COVID?

Pediatrician shares what we’ve learned since some schools opened last fall

by Steve Silvestro, MD  @zendocsteve

Published February 7, 2021

Note: SARS-CoV-2 is the proper name of the virus, while COVID-19 is the name of the disease it causes. For simplicity, I use the term COVID throughout this article.


The countdown is on!

There are just a few weeks left between right now and the date our school district has set to consider reopening schools for the first time since last March.

As you might expect, emotions are riding high in the community right now—and people have dug in their trenches. Some argue that kids absolutely need to be back because they’re suffering emotionally and academically. Others believe that schools shouldn’t open until teachers and staff are 100% vaccinated. And still more are left torn, feeling as if there really is no good answer at all.

And I can’t blame any of them—we’ve flip-flopped a half dozen times on what we think kids’ role is in transmitting COVID and whether or not schools might fan the flames of the pandemic.

But now that we’ve had half a schoolyear in which nearly 50% of American kids have been going to school either fully in-person or hybrid, the data is finally starting to come together.

So what does it say?


Let me first tell you that I spent much of last summer and the early part of the fall in the camp of those arguing that schools really shouldn’t open, at least not for kids over 10 based on the info we had at the time.

But as data has trickled in from areas that have had kids in school since the fall, I’ve swung to the other side—slowly and cautiously at first, and now with a bit more confidence.


Looking at research from around the country, most signs point to the idea that schools are not sites of rampant COVID spread. In fact, some studies have found that if COVID spreads in schools at all, it’s significantly less than what happens in the surrounding community.

Let’s take a look:

One study examined 11 schools in North Carolina that had students in school either full-time or on a hybrid model over the first 9 weeks of the schoolyear. Out of 90,000 students and staff in these schools, 773 contracted COVID somewhere outside of school—while only 32 people out of the 90,000 were found to have been infected in school. What’s more, almost half of those who caught it in school (15) were in classes that were either not wearing masks at all (pre-K classes that, at the time, were not required to do so) or had kids who ate lunch in close proximity to each other.

Another study looking at 17 schools in rural Wisconsin found that transmission in schools paled compared to that in the community. There were over 5,500 students and staff in all, with two-thirds of the students in grades 7-12—kids of an age usually considered more high-risk for catching and spreading COVID. But over three months, only 7 cases of COVID were determined to be caught in school. That’s a rate of 126 per 100,000 people over three months—far lower than the surrounding community’s rate of 5,466 infections per 100,000 people over the same timeframe.

Now bear with me as I take 60 seconds to dig into the math here—because this is really important. Last fall, I talked about the stats you could use to consider “opening your family up.” The target I discussed was for community daily new cases to be at 4 or less per 100,000 people—with around 1 per 100,000 people considered on track for containment. Well, the numbers we just talked about in that Wisconsin study were over a three-month period of 91 days. If we convert these to daily rates (i.e., divide by 91), then we see that the surrounding community had 5,466/91 = 60 new cases per day per 100,000 people—a rate that’s very high, similar to what most of the country saw around December and January. But the 17 schools only had a paltry 1.4 new cases per day per 100,000 people. In the face of COVID spreading like wildfire in the community, Wisconsin schools had it contained.

To nail this idea down and figure out how risky school is compared to other types of gatherings, researchers compared school-aged kids in Mississippi who tested positive versus those who tested negative. They found that going to school or daycare in the previous two weeks had no impact on whether or not kids tested positive. What did? Attending parties, playdates, weddings, and other indoor social gatherings with people outside of one’s household. What else stood out—kids who tested positive had a higher rate of exposure to people not wearing masks.


This is the big question—one that’s weighed heavily on the minds of teachers, unions, and many parents and administrators. Fortunately, the evidence seems to look really good for teachers and staff, as well.

That study of 17 schools in Wisconsin? While there were 184 students and staff who contracted COVID from elsewhere in the community, zero of the 7 people who caught COVID in school were teachers or other staff members.

Now, that’s not to say that it’s impossible for teachers and staff to contract COVID from exposures at school. But similar findings have been observed around the world. Data from Sweden, Norway, England, Denmark, and France has shown that teachers and staff have no higher rate of COVID infection than people with any other occupation in the community.


So how does this work? How do schools seem to avoid rampant spread, despite having classrooms filled with people who don’t live in the same house?

To paraphrase my friend and fellow pediatrician Cara Natterson: “Schools follow the rules.”

There is a common thread among restaurants, bars, and the homes of family and friends—the settings that have led to the most consistent viral spread: They all have low rates of mask-wearing and questionable social distancing.

Schools, however, find success in tamping down spread by setting rules and sticking to them.

The schools in that Wisconsin study had a 92-97% rate of mask-wearing by students and staff. Kids were kept in cohorts of 11-20 students, with kids sitting at least 6 feet apart and next to the same children whenever possible. If a child was kept home due to COVID-like symptoms, that child’s siblings were kept home, as well.

Superintendents of schools in the North Carolina study noted that those same rules—as well as detailed planning, strict contact tracing, and sharing successful tactics with each other—were all key to keeping schools free from COVID spread.

The National COVID-19 School Response Dashboard, a joint venture organized by multiple education groups and economist Emily Oster, details exactly what works. Looking at reports comprising over 9 million students and 1.3 million staff, infection rates amongst students and staff are drastically lower in classes that 1). require students and staff to wear masks, 2). have lower density of students, 3). require distances of at least 3 feet, and 4). have improved ventilation. Importantly, this dashboard only looks at the number of people testing positive—it doesn’t report whether the students or staff contracted the virus in school versus outside of school. If they did, based on what we know from the studies above, we’d likely find that these mitigation measures have an even more significant impact at keeping students and staff healthy.


Of course, we know exactly what works—but we’ve got to stick to those rules so that they actually work well.

There’s a petition going around my community right now aiming to further delay reopening schools. It could carry some teeth—if the cases the author uses weren’t glaring examples of exactly what not to do.

In trying to show that schools lead to rampant spread, the author uses a report from Montreal claiming that schools drove spread in the community from September through January. But here’s the thing—students in Montreal weren’t required to wear masks at all in September, and then only high schoolers had to wear masks full-time beginning in October. Only in January—the end of the timeframe this report studied—did kids in grades 5 & 6 have to wear masks full-time, and kids in grades 1-4 still only have to wear them in public spaces throughout the school, but not in the classroom.

Of course there was rampant spread!

When schools don’t have strong masking & distancing rules—and adherence to them—that’s when we see them become COVID hotspots. The headline-grabbing spread through Israeli schools when they first opened in May is now attributed to overcrowded classrooms and the fact that kids were told not to wear masks due to a heatwave. A school in Connecticut had ten people contract the virus in school—5 students and 5 staff—when, according to the superintendent, “mitigation protocols broke down.”

It’s true that schools have the potential to lead to COVID spread—any public gathering does. But when they have detailed protocols and, most importantly, require mask wearing and physical distancing—then we see that schools become safer for students and staff than almost any other setting in the community.


There are a few other factors that may have an impact, but how much isn’t entirely clear.

First are community metrics. There is the general idea that the higher the spread in the community, the higher the risk of spread in schools. This makes sense—if there’s more COVID present in the community, odds are higher that someone will walk into school with it. Plus, it’s hard to do good contact tracing and figure out whether people are catching it in school or outside of it when there are many more people with COVID to try and trace. Unfortunately, the few studies that have tried to nail down community metrics that make schools less safe use data from communities and schools where rates of mask-wearing are low.

Looking at the National COVID-19 School Response Dashboard–which, again, doesn’t distinguish between students and staff infected in school versus out of school—the rates of infected staff and students in schools with strong mask and distancing protocols tend to be the same or better than others in the community when the surrounding community’s new daily cases are 20 or fewer per 100,000. If the dashboard were to distinguish between infections caught in school versus out of it, we might find that schools effectively mitigate spread at even higher community case rates.

One other thing to keep in mind is that opening schools doesn’t necessarily mean opening all school-related activities. Certain school sports, like wrestling and hockey, have been implicated in clusters of spread.


This is the million-dollar question, one that’s going to cause the most strife now that vaccines are available but still hard to get.

The new head of the CDC, Rochelle Walensky, recently said that based on the data we have, vaccinating teachers “is not a prerequisite for safe reopening of schools.” The White House initially walked that statement back, fearing it would be viewed as anti-teacher, before eventually lining back up with Walensky’s sentiment a few days later. Shortly thereafter, former CDC Director Tom Frieden made a similar argument.

Now, I’m going to out myself here as a liberal, pro-teacher guy with strong labor union ties in my family. My wife is a teacher—emotionally, I’d love for her to have had a vaccine yesterday. But rationally, looking at the data we have from half a schoolyear of kids going in-person around the country, the vaccine may not be the battle to fight over—especially knowing that we’d likely need another 2-month period for everyone to get both doses and time for them to kick in.

Instead, the battle that seems most worth fighting is making sure school districts have nailed down exhaustive, detailed planning on masks, distancing, keeping low density in classrooms, and other mitigation protocols. Teachers should absolutely get vaccinated early on, but when it comes to requirements for opening, these other factors are the absolute-musts that teachers, parents, and administrators should push hardest to see in place.

That said, there are settings in which these plans and protocols are less feasible. Some schools may not have classrooms that allow for adequate distancing, and both masking and distancing may be issues in special needs classes. In these situations, pushing for early teacher vaccination may be the best option.


Here’s the deal: Infection rates in many places in the U.S. are currently falling. Sure, we don’t know whether that will continue once the new, more contagious variants spread—although the vaccines we have appear to be fairly effective against most of them and should help with community spread.

But now—as proposed metrics for reopening quickly approach—now is the time to finalize detailed plans for what’s going to happen when schools open back up. The data is there, showing it can be done and exactly how to do it—now isn’t the time to kick the planning can down the road.

Just as important is that those plans are openly, unabashedly communicated to teachers, staff, and parents. I can tell you that in my community, even though our school district has set guidelines for when schools might reopen based on community infection numbers, most parents—and even teachers and staff!—will tell you that they still don’t know exactly what protocols will be in place should schools finally open. Whether or not the actual planning for reopening is lacking, communication about the specifics of planning has been. The same can be said for many other areas around the country. That poor communication only fans the flames of worry and doubt in parents’ and teachers’ minds, encouraging different groups to continue to make emotional arguments rather than ones rooted in science.

But the science is here. The data has arrived. It’s time to use that science, to fight misinterpretations of it, and to make smart, clearly communicated decisions as a result.

One year into the pandemic and six months into a new U.S. schoolyear, the evidence has coalesced into a clear picture: Using simple mitigation protocols—and sticking to them—schools can be very COVID-safe for both students and staff.