An excruciating choice faces school communities: risk COVID-19 exposure by returning to classrooms, or court emotional and developmental harm, and child-care nightmares, with another season of virtual learning.

New data from two South Jersey counties provide a window into how much of a hazard COVID-19 could pose for reopening. Children and teenagers account for a growing share of coronavirus cases in Camden and Gloucester Counties, mirroring a national — and ominous — trend as young people rebel against social distancing rules, health experts say.

In those two counties, people under age 20 accounted for almost 13% of confirmed cases in the last month, compared with less than 2% in a four-week period this spring. Camden and Gloucester Counties officials have made public the age of every confirmed case. That’s a step no other county in the area has taken, so it’s not possible to compare them directly with the rest of the region. But experts say the lessons of the data are apparent.

“I think it’s very clear we should expect there will be outbreaks among children and teenagers if schools open,” said David Rubin, a pediatrician and director of PolicyLab at Children’s Hospital of Philadelphia. “If the disease burden in the community is too high, the risk in schools is too high.”

Many districts in Southeastern Pennsylvania are planning fully virtual starts to the year. State officials this week recommended that schools make reopening decisions based on rates of community spread — guidance that placed Philadelphia and its collar counties into a “moderate” transmission range, warranting either part-time in-person instruction or fully remote plans.

New Jersey’s governor reversed course Wednesday on a mandate that schools offer some in-person classes, saying schools can shift entirely to virtual learning in the fall if they can’t meet the state’s health and safety guidelines, including standards for ventilation, access to face masks, and training for staff on hybrid learning and cleaning.

“We are fully committed to getting this right for students, our educators, our districts and every family, that everyone who enters one of our schools goes safely home at night,” Gov. Phil Murphy said in a news conference.

The decision came in response to school district administrators who had informed state officials they would not be able to safely accommodate students by September. The majority of schools will be likely able to accommodate partial in-person classes, state officials said.

Experts acknowledge that keeping kids out of school has significant consequences for their educational and social development, creates hardship for parents who struggle to balance child care and work, and disadvantages children who don’t have access to technology.

“The reality is, now we know about mental health and emotional health, these things have fallout,” said Haleh Rabizadeh Resnick, a Cherry Hill mother with one child in public high school and the other in middle school. Even with Murphy’s change in direction, she hopes for some form of in-person classes, she said.

“Our new reality is to live at a slightly higher danger level,” she said.

Other parents, though, balk at sending their children to school.

“There’s way too many variables, way too many unknowns at this time for me to feel comfortable sending my child out,” said Elliott Castillo, also of Cherry Hill, who signed up for virtual learning for his daughters, ages 12 and 8.

Young people’s burden

Camden and Gloucester Counties had between 33% and 40% fewer cases among people of all ages in the last month than they did at the state’s peak in April, when almost 4,000 people were confirmed to be infected. There were 188 confirmed cases among those 19 and younger in the two counties over the last month.

But the burden of cases shouldered by children and teenagers is growing, a shift that can’t be accounted for just by testing practices, said Caryelle Lasher, assistant public health coordinator for Camden County’s department of health and human services.

“There are going to be a lot of variables at play that are going to make it very difficult for a lot of schools to achieve a safe classroom structure,” she said.

In the last four weeks, 14% of Camden County’s cases have been 19 or younger. Through much of April, they accounted for just 2% of the county’s confirmed cases. In Gloucester County, those under 20 accounted for 11% of cases in the last four weeks, compared with 1% during a four-week period from early April to early May.

The American Academy of Pediatrics reported that while children make up just 9% of the nation’s COVID-19 positive cases, there were 179,990 new cases among children from July 9 to Aug. 6, a 90% increase in a matter of a month.

With some rare and serious exceptions, children are mostly spared the worst health complications from COVID-19, yet they could spread the virus to more vulnerable family members.

“If the question is, are kids able to transmit the virus to each other or to an adult,” said Richard Malley, senior physician at Boston Children’s Hospital’s division of infectious diseases and a professor at Harvard Medical School, “the answer is unquestionably yes.”

The dimensions of the risk, as with so much else about the new virus, are not clear.

“What I’m hearing is such a wide range, and a developing range, from epidemiologists, I can’t put my — as a nonprofessional — finger on it,” Lower Merion Superintendent Robert Copeland said during a school board meeting last week. He recommended that the district begin the year virtually.

Weighing risks

An article in the New England Journal of Medicine last month recommended that at least elementary schools reopen, and described a number of European and Asian nations that have safely restarted school. Yet unlike the United States, which is still producing record-setting numbers of cases, those countries had low transmission rates and kept kids safely apart from each other.

Another study released this month found minimal spread of the virus in 15 Australian schools and early child-care centers with reduced student populations despite some children and adults having attended with the virus.

A study released in July from South Korea indicated children 9 and younger were less likely to transmit the disease within a household, but that advantage vanished in older children and teenagers. The same study also anticipated higher rates of infection once the youngsters return to school.

Yet, recent studies from other researchers indicate children with symptoms of COVID-19 are more likely to spread it, according to a report in the Journal of the American Medical Association.

Behavior as much as biology may matter to childhood spread. Kids may not wear masks properly or at all (though plenty of adults don’t either), and young children are not known for frequent hand washing or social distancing, said Karen Ravin, chief of infectious diseases at Nemours/Alfred I. duPont Hospital for Children.

Rubin, of CHOP, said the Philadelphia region isn’t ready to take on the risk of in-person education.

“We haven’t gotten ourselves yet, in most areas of this country, where we’ve eliminated enough virus as possible so that these school plans have eliminated the likelihood of a presymptomatic or symptomatic kid bringing it into a classroom,” he said.

Just a few infected children could spur a community outbreak. About 17% of the nation’s teachers are 55 or older, the New England Journal of Medicine reported, and more susceptible to serious symptoms from the virus. But younger teachers and parents with preexisting conditions as common as diabetes also are vulnerable.

Summer camps in Georgia and Missouri both saw COVID-19 cases spread rapidly. The New England Journal article noted that when Israel attempted to reopen schools without distancing and minimal precautions, cases spiked. The New York Times reported that without mandatory masks, social distancing and other measures, an outbreak at one high school in Jerusalem infected hundreds of faculty, students, and families.

An unenviable choice

Some Camden County communities have seen children and teens become the largest single age block with confirmed COVID-19 cases. Haddonfield, Camden County, has had just 14 cases in the past month, but half were in 10- to 19-year-olds. In Cherry Hill, just 3% of cases were under 20 years old during four weeks in early April to early May — compared with 29% of cases in the last four weeks.

House parties, swim clubs, and contact during sports all could be at work, Lasher said, noting that the virus spreads most efficiently indoors.

“We’re seeing a lot of sibling clusters,” she said.

Health experts are eyeing Labor Day weekend’s celebrations and trips nervously. Rubin fears schools could incubate cases just as nursing homes did early in the pandemic.

“We’ve gone through multiple chapters of this story, and they all involve some level of gathering,” said Rubin, who recommends that schools wait until closer to early October before physically reopening.

In Camden County, Lasher said, transmission most often seems to go from adult to child. Children who have tested positive while attending day care have largely not spread the virus to their peers, she said. But whether that experience translates to other ages and settings isn’t known.

One reason for the uncertainty: Because of widespread stay-at-home orders in March, we do not know what will happen when many children are exposed.

“The fact that every city, every county, every state is doing things a little bit differently, which is not ideal, it lends to confusion; at the same time it means there’s a bit of a randomized clinical trial going on,” Malley said. “I’m not saying it’s a good thing. I’m saying it’s a reality.”

Clearing the record: This story has been updated to correctly report David Rubin’s recommendations for when schools might reopen.