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Monday, March 25, 2024

A Summer Camp Covid-19 Outbreak Offers Back-to-School Lessons

As policymakers, school administrators, and public health officials in the US fiercely debate whether it’s safe to reopen schools at the end of the summer, one of the biggest stumbling blocks has been a lack of reliable information about how easily children and young people can spread the virus that causes Covid-19. But that data is starting to trickle in. A few super-spreading events involving kids have been documented so far: a private school in Chile, a childcare center in Australia, and now, several summer camps in the US. At one, in Georgia, more than 250 children and young adults tested positive for the novel coronavirus, according to a recent report by the US Centers for Disease Control and Prevention.

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By Eve Sneider

The agency’s analysis shows that, contrary to some early studies, children of all ages can get infected, pass the virus on to others, and, the authors write, “might play an important role in transmission.” Public health experts say the outbreak, coupled with newly published research on coronavirus spread among children, has a lot to teach decisionmakers about how to proceed with school reopening plans as cases continue to surge uncontrollably throughout many parts of the country.

This single outbreak at a summer camp in northern Georgia is a case in point, showing how rapidly the infection can spread among kids once they’ve been returned to any sort of typical social network. In mid-June, about 250 counselors, staff, and trainees arrived at YMCA Camp High Harbour, on the shores of Lake Burton. A two-hour drive from Atlanta, the camp typically hosts about 4,000 school-age kids every summer, offering both daylong and overnight programs. But this year was anything but typical. While the High Harbour counselors and staff sat through a three-day orientation, the state of Georgia reported a record-high 4,689 daily new coronavirus cases. The following Monday, June 21, High Harbour staffers welcomed their first wave of campers.

In keeping with the safety measures outlined by Governor Brian Kemp’s executive order allowing overnight camps to operate, all of them—staff members, trainees, and campers—were only allowed on the premises once they had provided proof of a negative SARS-CoV-2 test taken sometime in the previous 12 days. Officials from the YMCA of Metropolitan Atlanta, which operates the camp, were hopeful these precautions and others would help the camp open safely, restoring a sense of normalcy in the lives of campers and their parents. Many of these families reached out, urging the organization not to cancel its overnight programs, officials from the YMCA of Metropolitan Atlanta wrote in a statement emailed to WIRED: “This weighed heavily on our decision to open, a decision in retrospect we now regret.”

On the evening of June 22, the day after campers arrived, a teenage staff member came down with the chills. The next day, they were tested. On Wednesday, the test results came back positive for SARS-CoV-2. Parents were notified and campers sent home. The public health department was called in. Days later, the camp closed. By mid-July, an investigation by The Atlanta Journal-Constitution found that the virus had spread to dozens of campers and counselors. According to the CDC’s investigation, which identifies High Harbour as “Camp A,” there were actually hundreds of infections among campers and staff, rather than dozens.

However, understanding the true scope of the outbreak has been limited by incomplete data. The CDC had testing information for only 344 of the 597 campers and staffers, which its scientists noted meant they could be missing some cases. Of those who were tested, 168 campers came up positive, along with 92 staffers and trainees. For those who tested positive, 51 were between the ages of 6 and 10, 180 were ages 11 to 17, and the remaining 29 were adults. CDC scientists calculated the attack rate—the percentage of camp attendees who tested positive out of total attendees—which, they noted, is likely an underestimate because of potential missed cases among people not tested. Despite this, the attack rate was high across all age groups, and highest among the staff members who had been at the camp the longest.

Some early studies, based on data out of China, showed that while children tend to not get very severe symptoms of Covid-19, the virus can infect them just as easily as adults. But as the virus raced around the globe, infecting millions, children continued to account for a very tiny fraction of recorded Covid-19 cases. That led many to believe that because kids tend to have mild or absent symptoms, they’re unlikely to spread the virus to others. Literature reviews, like this one and this one, added credence to that belief.

But some scientists have levied critiques against this conclusion, citing a lack of directly measured data, unaccounted biases, and other methodological flaws. These include the fact that for much of the pandemic, many kids have been shielded from potential exposures by school closures and concerned parents. Studies conducted in countries where officials reopened their schools found that transmission among kids was low in Norway, Denmark, and parts of Germany that had an overall low incidence of the virus, and where school officials shrank class sizes and adopted social distancing practices on campus, while countries like Israel faced rampant outbreaks after reopening without making these changes.

And milder symptoms mean kids often don’t get tested, and then their infections—and role in any subsequent spread—go unrecorded. “A lot of people have internalized this message that kids are just not important, and I don’t think we really have the evidence to say that,” says Tara Smith, an epidemiologist at Kent State University. “In fact, we have increasing evidence to the contrary.”

Some of that evidence arrived last week in a July 30 JAMA Pediatrics research letter. Scientists at Northwestern University and the Ann & Robert H. Lurie Children’s Hospital of Chicago analyzed swabs taken from inside the nasal cavities of 145 kids who were tested at sites around Chicago. They were tested within the first week of their showing symptoms of Covid-19 or experiencing a high-risk exposure. The researchers quantified how much genetic material from SARS-CoV-2 was in each swab and found that older kids had viral loads similar to those of adults. Surprisingly, they found that children under the age of 5 had 10 to 100 times more copies of the virus than either older kids or adults. The findings suggest that if young kids shed viral particles at the same rate as older kids and adults, they could be a significant driver of new infections.

But that’s a big if. A large study from South Korea published last month found that children younger than 10 appear to not transmit the virus as much as those between the ages of 10 and 19.

Looking at these two studies and the CDC report, Ashish Jha, epidemiologist and director of the Harvard Global Health Institute, says transmissibility among children is still a big question mark. “My best reading of the evidence is that older kids, high schoolers, we should treat them as adults. Younger kids, let’s say K-5, they probably transmit less, maybe as much as 50 percent less,” he told reporters during a press call Monday morning. Middle schoolers likely fall somewhere in between, he said. “It seems like it really is about the size of the human—how much air they are expelling. There’s a whole bunch of mechanical and physical issues that go into this.”

In other words, it’s not just a matter of how many viral particles are in a kid’s nose; it’s how effective they are at breathing them onto other people. Smaller lungs push out less air, but kids also breathe more quickly than adults. Exactly how these factors translate into transmissibility is still far from understood. It would require large, expensive studies combining longitudinal testing, intense contact tracing, and genetic analyses to trace the virus’s evolution across individuals, and lab studies to measure where particles leaving a kid’s nose and mouth ultimately wind up.

Much more settled is that most kids who contract Covid-19 don’t get that sick. Data from the CDC report about symptoms among High Harbour staffers and campers was available for only 136 patients, with most showing mild symptoms including fever, headache, and sore throat. About a quarter of infected people reported no symptoms at all. The study did not say whether anyone had been hospitalized. (For questions about the outbreak, a Georgia Department of Public Health spokesman referred WIRED to the CDC report.)

According to the report, High Harbour followed many of the CDC’s recommendations for summer camps, including enhanced cleaning and disinfection procedures, staggering the use of communal spaces, and requiring physical distancing outside of cabins. But other recommendations regarding the use of masks and increasing ventilation whenever possible, were not followed. The report found that camp leaders did not require open windows and doors to increase air circulation, which is necessary to prevent the build-up of virus-containing aerosols. And while staff were required to wear cloth masks, High Harbour did not ask campers to do so. (Officials of the YMCA of Metropolitan Atlanta did not contest these details, saying only in their statement that High Harbour made every effort to follow CDC guidelines and has cooperated with the agency in its investigation.)

The CDC report concluded that in 28 of the camp’s 31 cabins, at least one person, and often many, tested positive. “Relatively large cohorts sleeping in the same cabin and engaging in regular singing and cheering likely contributed to transmission,” the CDC report authors wrote. Evidence for airborne transmission of SARS-CoV-2 has been building for months, making it clearer just how important the roles of masks, physical distancing, and good ventilation are in stemming the disease’s spread.

In an emailed statement, officials at the YMCA’s national office told WIRED that the organization worked with the American Camp Association, the CDC, and a consortium of infectious disease, medical, and sanitation experts to publish health and safety guidelines for all Y camps, to use in determining if and how they could operate. “While the majority of YMCA day camps have opened this summer, the vast majority of our overnight camps chose not to open. Of those overnight camps that did open, we are not aware of any other Covid-19 outbreaks, nor are we aware of any camps that chose to close in reaction to the situation at High Harbour,” they wrote.

States are required to report any positive cases of Covid-19 to the federal government, a process which has been complicated as of late due to a disastrous data-collection turf war between the CDC and the Department of Health and Human Services. But they’re not required to keep tabs on summer-camp-specific outbreaks. That makes it hard to know if the High Harbour outbreak is an outlier or a signifier of what awaits efforts to reunite children with IRL classrooms.

Many state public health departments that WIRED contacted did not collect information about outbreaks at summer camps, or would only provide it under a formal records request. One state that did have that data was Vermont, with zero summer camp cases to report—which makes that state exceptional in more ways than one. Right now, Jha said, Vermont and Maine look like the parts of the European Union that best prevented community spread of the virus. That means countries like Norway, Denmark, and Germany, which were able to reopen schools without runaway viral spread. The low case incidence, combined with strong safety measures, should make it pretty safe for these northeastern states to send their kids back to school, Jha said. Over the past week, Vermont has had an average of four cases per day, according to data collected by The New York Times. Maine has had 20. Case rates in both states are trending down. By comparison, in the last week Georgia has recorded an average of 3,372 daily cases, an increase of 13 percent from the average two weeks earlier.

Read all of our coronavirus coverage here.

Amy Wesolowski, an infectious disease epidemiologist at the Johns Hopkins Bloomberg School of Public Health, says the High Harbour example shows that asking for proof of negative coronavirus tests before large gatherings isn’t a sufficient preventative tactic on its own. These tests can miss someone in the early stages of infection—before the virus has replicated to detectable levels. People can also get exposed in the time it takes to receive their results, and may attend future gatherings thinking they are in the clear, even though those test results are now outdated.

“The fact that these places tested beforehand and still saw all this child-to-child transmission suggests a big problem for schools,” she says. True, a sleepaway camp isn’t a perfect comparison to a classroom, she admits. But both instances involve kids spending hours in close proximity, usually indoors. And with schools and many day care centers shut down for months, there haven’t been many opportunities in the US to study what happens when you put lots of kids together under one roof. “I think it’s a good warning that even if you really try to do a lot, take a lot of recommended safety precautions, it’s still possible to get transmission, even in kids," she says.

The lack of consistent access to quick testing in the US right now only exacerbates these issues. In one of the first school districts in the US to reopen, in Indiana, just hours into the first day of classes, a call from the county health department notified the school that one of its students’ tests had come back positive, The New York Times reported over the weekend. A high school in Mississippi has also sent 40 students into quarantine after three tested positive shortly after the start of the semester.

About two-thirds of states in the US, largely in the South and West, are currently experiencing “uncontrolled” community spread, according to public health researchers at Covid Exit Strategy, a nonpartisan group tracking state-by-state testing and hospitalization data. Opening schools in these areas is likely to lead to outbreaks. Jha predicts that even for states and counties that have stabilized, it’ll take a lot more work to add the layers of protection necessary for opening safely. That means things like ventilation upgrades, adding outdoor teaching space, requiring masks and physical distancing, and providing regular testing to everyone on campus. There are serious educational and developmental penalties to not opening schools, he says, especially for the youngest kids. Because of this, schools should prioritize plans for kids aged K-5. But the cost of not getting it right is also huge.

“An outbreak will shut down a school for a long time,” he said. People will get spooked. It’ll be back to Zoom. And the kids who suffer most will be those in poor communities with limited access to the internet, who rely on schools for more than education, including after-school care and meals. “We only get one shot at opening schools this fall,” said Jha.

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