Into the con column went a study from Chicago that found children carry large amounts of virus in their noses and throats, maybe even more than adults do. Also in the con column: two South Korean studies, flawed as they were, which suggested children can spread the virus to others — and made me wonder whether my sixth-grader, at least, should stay home.

Reports from Europe hinting that it was possible to reopen schools safely dribbled onto the pro side of my ledger. But could we match those countries’ careful precautions, or their low community levels of virus?

I live in Brooklyn, where schools open after Labor Day (if they open this year at all), so my husband and I have had more time than most parents in the nation to make up our minds. We’re also privileged enough to have computers and reliable Wi-Fi for my children to learn remotely.

But as other parents called and texted to ask what I was planning to do, I turned to the real experts: What do we know about the coronavirus and children? And what should parents like me do?

The virus is so new that there are no definitive answers as yet, the experts told me. Dozens of coronavirus studies emerge every day, “but it is not all good literature, and sorting out the wheat from the chaff is challenging,” said Dr. Megan Ranney, an expert in adolescent health at Brown University.

But she and other experts were clear on one thing: Schools should only reopen if the level of virus circulating in the community is low — that is, if less than 5 percent of people tested have a positive result. By that measure, most school districts in the nation cannot reopen without problems.

“The No. 1 factor is what your local transmission is like,” said Helen Jenkins, an expert in infectious diseases and statistics at Boston University. “If you’re in a really hard-hit part of the country, it’s highly likely that somebody coming into the school will be infected at some point.”

On the questions of how often children become infected, how sick they get and how much they contribute to community spread, the answers were far more nuanced.

Fewer children than adults become infected. But childhood infection is not uncommon.

In the early days of the pandemic, there were so few reports of sick children that it was unclear whether they could be infected at all. Researchers guessed even then that younger children could probably catch the coronavirus, but were mostly spared severe symptoms.

That conjecture has proved correct. “There is very clear evidence at this point that kids can get infected,” Dr. Ranney said.

As the pandemic unfolded, it also appeared that younger children were less likely — perhaps only half as likely — to become infected, compared with adults, whereas older children had about the same risk as adults.

But it’s impossible to be sure. In most countries hit hard by the coronavirus, lockdowns and school shutdowns kept young children cloistered at home and away from sources of infection. And when most of those countries opened up, they did so with careful adherence to masks and physical distancing.

Children may turn out to be less at risk of becoming infected, “but not meaningfully different enough that I would take solace in it or use it for decision making,” said Dr. Ashish Jha, dean of the Brown University School of Public Health.

In the United States, children under age 19 still represent just over 9 percent of all coronavirus cases. But the number of children infected rose sharply this summer to nearly half a million, and the incidence among children has risen much faster than it had been earlier this year.

“And those are just the kids that have been tested,” said Dr. Leana Wen, a former health commissioner of Baltimore. “It’s quite possible that we’re missing many cases of asymptomatic or mildly symptomatic children.”

In the two-week period between Aug. 6 and Aug. 20, for example, the number of children diagnosed in the United States jumped by 74,160, a 21 percent increase.

“Now that we’re doing more community testing, we’re seeing higher proportions of children who are infected,” Dr. Ranney said. “I think that our scientific knowledge on this is going to continue to shift.”

Children do become sick with the virus, but deaths are very rare.

Even with the rising number of infections, the possibility that panics parents the most — that their children could become seriously ill or even die from the virus — is still reassuringly slim.

Children and adolescents up to age 20 (definitions and statistics vary by state) represent less than 0.3 percent of deaths related to the coronavirus, and 21 states have reported no deaths at all among children.

“That remains the silver lining of this pandemic,” Dr. Jha said.

But reports in adults increasingly suggest that death is not the only severe outcome. Many adults seem to have debilitating symptoms for weeks or months after they first fall ill.

“What percentage of kids who are infected have those long-term consequences that we’re increasingly worried about with adults?” Dr. Ranney wondered.

Multisystem inflammatory syndrome, a mysterious condition that has been linked to the coronavirus, has also been reported in about 700 children and has caused 11 deaths as of Aug. 20. “That’s a very small percentage of children,” Dr. Ranney said. “But growing numbers of kids are getting hospitalized, period.”

Children can spread the virus to others. How often is still unknown.

Transmission has been the most challenging aspect of the coronavirus to discern in children, made even more difficult by the lockdowns that kept them at home.

Because most children are asymptomatic, for example, household surveys and studies that test people with symptoms often miss children who might have seeded infections. And when schools are closed, young children don’t venture out; they tend to catch the virus from adults, rather than the other way around.

To confirm the direction of spread, scientists ideally would genetically sequence viral samples obtained from children to understand where and when they were infected, and whether they passed it on.

New York City has delayed the opening of schools by 10 days to give teachers and principals more time to prepare and to avert a possible teachers’ strike.

Under pressure from schools and advocates, the federal government has agreed to make it easier for schools to feed poor children.

“I keep saying to people, ‘It’s so hard to study transmission — it’s just really, really hard,’” Dr. Jenkins said.

Still, based on studies so far, “I think it still appears that the younger children might be less likely to transmit than older ones, and older ones are probably more similar to adults in that regard,” she said.

Sadly, the high numbers of infected children in the United States may actually provide some real data on this question as schools reopen.

So what’s a parent to do?

That’s a tough one to answer, as parents everywhere now know. So much depends on the particular circumstances of your school district, your immediate community, your family and your child.

“I think it’s a really complex decision, and we need to do everything we can as a society to enable parents to make this type of decision,” Dr. Wen said.

There are some precautions everyone can take — beginning with doing as much outdoors as possible, maintaining physical distance and wearing masks.

“I will not send my children to school or to an indoor activity where the children are not all masked,” Dr. Ranney said.

Even if there is uncertainty about how often children become infected or spread the virus, “when you consider the risk versus benefit, the balance lies in assuming that kids can both get infected and can spread it,” Dr. Ranney said.

For schools, the decision will also come down to having good ventilation — even if that’s just windows that open — small pods that can limit how widely the virus might spread from an infected child, and frequent testing to cut transmission chains.

Teachers and school nurses will also need protective equipment, Dr. Jenkins said: “Good P.P.E. makes all the difference, and school districts must provide that for the teachers at an absolute minimum.”

As long as these right precautions are in place, “it’s better for kids to be in school than outside of school,” Dr. Jha said. “Teachers are reasonably safe in those environments, as well.”