Pictures of packed school hallways in Georgia and news of positive tests on the first day of classes in Indiana and Mississippi sparked the latest fraught discussions over the risk the coronavirus presents to children — and what’s lost by keeping them home from school.

For months, parents and teachers, epidemiologists and politicians have chimed in with their views on the many still-unanswered questions about the extent to which the virus is a threat to children — and the extent to which they can fuel its spread.

children tested positive for the coronavirus in the last two weeks of July, more than a quarter of the total number of children diagnosed nationwide since March.

President Trump has repeatedly maintained the virus poses little threat to children.

Doctors are more confident that most children exposed to the virus are unlikely to have serious illness, a sentiment backed by a report published Friday by the Centers for Disease Control and Prevention that concluded children are far less likely to be hospitalized with covid-19, the illness caused by the virus, than adults.

But when children do fall seriously sick, the burden of illness is borne disproportionately: That same CDC report concluded that Hispanic children are approximately eight times more likely and Black children five times more likely to be hospitalized with covid-19 than their White peers.

But accumulating evidence suggests the coronavirus may affect younger children differently than older ones.

For example, doctors say the multisystem inflammatory syndrome linked to the virus — known as MIS-C — that has appeared in a small number of children weeks after infection presents differently in younger children than in teens and young adults.

One paper published in July in the journal JAMA Pediatrics found that children younger than 5 with mild to moderate cases of covid-19 had much higher levels of virus in their noses than older children and adults — suggesting they could be more infectious.

Children under age 10 did not appear to pass on the virus readily, while those between 10 and 19 appeared to transmit the virus almost as much as adults did.

In June, an overnight YMCA camp in Georgia was forced to close after 260 of 597 children and staff members tested positive for the virus — an event some experts heralded as a parable for what can happen when young people are allowed to gather without being attentive to wearing masks or maintaining physical distance.

Khan, an assistant professor of cardiology and preventive medicine at Northwestern University’s Feinberg School of Medicine, said social practices, rather than biology, may explain why teens and young adults appear to be spreading infection.

They are more likely to not have experienced any consequences,” Khan said.

With the coronavirus pandemic, like any disease outbreak, research takes time, and experts say decisions being made about reopening schools are necessarily being made without the full picture of the risk the virus poses to children.

Did one teenage counselor spread the virus to the whole camp?

Did they bring the virus back to their families, thereby dispelling the notion that children do not transmit the virus to adults?

As the case of the Georgia camp illustrates, measuring the risk younger children face in returning to school continues to be an inexact art.

Teachers unions from Florida to Ohio have protested plans to fully reopen schools, arguing that even if a few months of data suggests children are not likely to suffer severe outcomes from the virus, they could still pass it to vulnerable adults.

John Cochran, the father of a ninth-grader and middle-schooler in the Georgia school system, said in an interview he felt it wasn’t safe for his children to attend school in person, in part because multiple adults in their family are immunocompromised.