The delta variant of COVID-19 is more contagious for children. Is it making them sicker, too?

At Texas Children's Hospital, there are more patients with COVID-19 right now than at any point in the pandemic. Tennessee is getting close to its all-time high of kids sick with COVID-19. And at Joe DiMaggio Children’s Hospital in Hollywood, Florida, the number of children needing treatment for COVID-19 jumped from 20 in June to 200 in July – and has topped 160 so far in August.

Delta is clearly more contagious than previous variants, and it's tearing its way across the South, said Dr. James Versalovic, the Texas Children's interim pediatrician-in-chief.

What's not clear is whether kids are getting any sicker with delta than with other variants.

"Right now, it's speculative," he said.

He said the children he's seeing seem to have more fever and congestion than those treated during last summer's and winter's surges, he said. "We do think delta is maybe contributing to that."

But it's too soon to know whether they will have worse outcomes. "It is literally unfolding as we speak," Versalovic said. "We're going to be keeping a close eye on delta in children and adolescents."

'All of them': Tennessee health chief says children's hospitals will fill up as delta variant surges

Others were less convinced that delta is any different from its predecessors.

"I think kids are just being swept up in the firestorm raging in the South," said Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, also in Houston.

"In low vaccination areas like here in the South, it’s so transmissible – the community transmission or force of infection is like nothing we’ve seen – so everyone who is unvaccinated is at high risk of getting sick," he said.

Dr. Ashish Jha, dean of the Brown University School of Public Health, categorizes the likelihood that delta makes kids sicker a "maybe."

"It's not a slam dunk," he said.

Early studies looking at the alpha variant also indicated that it was likely more virulent than its predecessor, but it turned out not to be. "So we don't want to overreact," Jha said.

But arguably, if people carry a higher load of virus when infected with the delta variant – as they seem to – then the variant might also be more dangerous.

"The jury's out on this," Jha said. "We have to we have to get better data. But that may be contributing to what's happening."

Children under 12 are still not eligible for vaccination. Vaccine studies in kids were started later than in adults and older teens and are expected to be completed in the early fall.

How do we slow spread of delta variant? Get vaccinated, experts say.

It's extremely difficult to show whether one variant is more virulent than another, said Dr. Rick Malley, an infectious disease specialist at Boston Children's Hospital.

There are so many factors that affect the seriousness of an infection, he said, including the health of the child, the care they receive and whether those at highest risk have been vaccinated.

"My guess is delta is not particularly more virulent in children than others," Malley said. But with so many adults infected, it stands to reason that more children and teens will catch it, too, he said.

That's why the handful of public health experts USA TODAY spoke with said it's crucial for everyone who can be vaccinated against COVID-19 to get the shots. The more the virus can be slowed down, the fewer children will catch it, the experts said.

"It has been shown time and time again in different settings. The vaccination rate of the eligible population is directly related to how much this virus can adversely impact kids," Malley said.

Masks are also helpful, he said, particularly among children too young to be vaccinated. Unmasked children in close contact with one another – such as in a classroom – could pass on the virus. "If left unmasked and interacting with lots of others, you could imagine a child could serve as an important vector of transmission," Malley said.

Back to school? Delta variant has college professors 'freaking out' about fall 2021 semester

His hospital has not had an increase in cases, though he added, "I don't know if I should say 'yet.'"

Cases have been climbing again in Massachusetts, but more slowly than in the South. Vaccination rates in Massachusetts are relatively high: 64% are fully vaccinated and more than 73% are partially vaccinated.

Dr. William Schaffner, an infectious disease expert at the Vanderbilt University School of Medicine in Nashville, Tennessee, said the number of infections are rising in his state, where vaccination rates remain relatively low.

"The children's hospitals in our state are very busy," Schaffner said.

The best way to protect children too young to be vaccinated, he stressed, is to get everyone around them vaccinated. "If you live in a community where virus transmission is very low, schools are going to be quite safe," he said.

Schaffner said he is worried about what will happen when flu season starts this fall. Last year, masking and school closures essentially eliminated the flu, but he worries about the possibility of a "twindemic" this year.

One other concern, Versalovic said, is the rising number of cases of respiratory syncytial virus, or RSV, which can be caused by pneumonia, especially in young children. Texas Children's has counted 25 cases of children with both RSV and COVID-19, a mix that makes each worse, he said.

"This combination obviously has presented a formidable challenge for children's hospitals in this region and across the country," Versalovic said.

Despite it all, Versalovic said, his hospital is coping with the surge and what he expects will be climbing case counts among children.

"We're managing it and we're just now anticipating the weeks ahead with the beginning of the school year," he said. "Bracing ourselves."

Contributing: The Associated Press

Contact Karen Weintraub at kweintraub@usatoday.com and Adrianna Rodriguez at arodriguez@usatoday.com.

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.

This article originally appeared on USA TODAY: Is COVID delta variant making children sicker? Experts don't know yet.