U.S. Coronavirus Rates Are Rising Fast Among Children

As some schools begin in-person classes, data compiled by the American Academy of Pediatrics from the summer show that cases, hospitalizations and deaths from the coronavirus have increased at a faster rate in children and teenagers than among the general public.

The data set, which spans from May 21 to Aug. 20, varies from state to state, possibly obscuring differences in how the virus affects infants, young children and adolescents.

For example, many states group infants and teenagers into the same category. One state even includes people up to age 24. But the rise remains similar across states.

Young children seem to catch and transmit the virus less than adults, and children of all ages tend not to experience severe complications from it. But Dr. Sean O’Leary, vice chairman of the American Academy of Pediatrics’ committee on infectious diseases, said that substantial community spread in many parts of the United States corresponded with more infections among children.

The rise in reported cases comes in part from more widespread testing, but Dr. O’Leary said there was evidence that minors were becoming infected at a higher rate now than earlier in the year because hospitalizations and deaths among children had increased as well.

Although much is still unknown about how the virus affects young people, like adults, Black and Latino children who contract the virus are more likely to be hospitalized.

“Anyone who has been on the front lines of this pandemic in a children’s hospital can tell you we’ve taken care of lots of kids that are very sick,” Dr. O’Leary said. “Yes, it’s less severe in children than adults, but it’s not completely benign.”

Since the beginning of the summer, every state in the country has had an increase in the number of young people who have tested positive for the coronavirus, as a share of all cases. In late May, about 5 percent of the nation’s cases were documented in minors. By Aug. 20, that number had risen to more than 9 percent.

Some lawmakers have cited the lower likelihood of transmission among school-age children as a reason schools should reopen for in-person classes.

President Trump has said he would like to see schools fully reopen and falsely claimed in a video posted by his campaign that children were “virtually immune” to the virus. Facebook and Twitter later removed the video, saying it violated policies about misinformation around the virus. In July, Gov. Ron DeSantis of Florida, a Republican, claimed that “schoolchildren actually are not vectors for this.”

Dr. William Raszka Jr., a pediatric infectious disease expert at the Robert Larner, M.D. College of Medicine at the University of Vermont in Burlington, said research consistently showed that adults — not children — were driving the spread of the virus. Outbreaks at summer camps and schools, however, have demonstrated that transmission can, in fact, happen among children.

At a sleepaway summer camp in Georgia where hundreds were infected, 76 percent of campers and staff members whose test results were available to researchers had tested positive. The youngest campers, ages 6 to 10, were more likely to be infected than older campers.

It is clear that the virus can spread among children under certain circumstances, Dr. Raszka said. He worries about opening schools in places where infection rates are high, especially in areas that do not require people to wear masks or other proven mitigation measures to stop the spread of the virus.

Unlike the summer camp where children interacted almost entirely with other children and teenagers, schools holding in-person classes require interactions between students and their adult teachers and caregivers, who may be more vulnerable to severe complications.

“One of the challenges is that you just can’t separate schools from the community,” Dr. Raszka said. “When there’s a really high prevalence rate in the community and you open schools, there’s going to be a lot of transmission in schools.”

In June, a study published in Nature found that people under age 20 were approximately half as susceptible to contracting the virus as those older than 20. That lower likelihood of infection is reflected across many states. In Arizona, for instance, about 2,800 of every 100,000 residents have tested positive, whereas just over 1,300 of every 100,000 children in the state have tested positive.

That likelihood changes by age. Research consistently shows that teenagers are more likely to catch and transmit the virus than younger children, though the reasons are uncertain. Those 10 to 19 years old make up a larger share of cases than young children in all of the states that track the age groups separately.

The total number of children infected has doubled since the American Academy of Pediatrics and education groups recommended in early July that schools should reopen wherever possible. Despite the overall increases, experts said those guidelines still applied.

“There are a lot of places in the U.S. where it is potentially safe to reopen schools, even knowing that, yes, kids can get infected and, yes, sometimes kids can get severely infected,” Dr. O’Leary said.

Some success stories show that it is possible to stop transmission among children in places with low community levels of virus.

At four summer camps in Maine, a state with one of the nation’s lowest infection rates, aggressive testing and quarantining prevented those who tested positive after arrival from spreading the virus. Germany, Denmark and Norway have been able to keep schools open, thanks to a combination of low community transmission, fast and free testing, and rigorous contact tracing.