“There is definitely potential for spread of monkeypox” in day cares, schools, college campuses, prisons, and other similar settings, said Dr. Alexandra Brugler Yonts, an infectious disease specialist at Children’s National Hospital in Washington, D.C. She assisted in the FDA’s review of Jynneos—one of two smallpox vaccines licensed for treatment of monkeypox, and the safer of the two by far.

“Anywhere that close physical, skin-to-skin contact occurs—particularly of people who are in various stages of undress—there is risk,” she said.

All children and adults at the unidentified day care center in Champaign County, Ill., were being screened, and no additional cases had been identified, state health officials said Friday, adding that Gov. J.B. Pritzker has been in touch with the White House regarding the situation.

But schools and congregate living settings aren’t the only places ripe for spread, Brugler Yonts said. Also on her list of where transmission could occur: pools and waterparks—“not through the water, but through bumping up against someone with active lesions—especially in the summer, given the heat and tendency for minimizing clothing.”

Contact sports like football and wrestling could prove problematic too, she added.

“Hopefully outbreaks can be contained more locally, but as people continue to travel, participate in the [aforementioned] activities, and then with school starting soon…I think this is going to be more widespread. There have already been cases in almost every state in the U.S.”

As of Friday, 7,510 cases had been identified in the U.S., with the majority of cases in New York, California, and Florida, according to data from the U.S. Centers for Disease Control and Prevention. Every state except for Wyoming and Montana had cases identified.

More than 28,000 cases had been reported globally since January, virtually all in countries where monkeypox is not considered endemic, according to the CDC. The U.S. now leads the world in identified cases, followed by Spain, Germany, the United Kingdom, France, and Brazil. Only 345 cases have been seen since January in African countries where the virus is considered endemic. Eighty-one children had been infected as of late July, according to the World Health Organization.

Illinois health officials Friday said the U.S. Food and Drug Administration had authorized the use of Jynneos, licensed for use in adults 18 and older, for potentially affected children at the center, “without jumping through normal hoops.” Mobile testing and vaccination services were on-site, they added.

An FDA spokesperson told Fortune via email on Friday that the vaccine was being approved for such children via a “single patient expanded access investigational new drug application” submitted for each. Applications are processed “as quickly as possible” and approved “when no comparable or satisfactory alternative options are available and requested by the treating licensed physicians, who determine whether the benefits outweigh the probably [sic] risk.”

The spokesperson would not comment further on the possibility of general approval for the use of Jynneos in children.

Because Jynneos is licensed, not just authorized under an emergency use authorization like initial COVID vaccines were, it can be used “off label”—for instance, given to children who have been exposed, Brugler Yonts said.

Researchers “will certainly want to collect safety and, if possible, immunogenicity data on these kids and follow them closely, since there is no preexisting data for use in the pediatric population,” she said. “But Jynneos is safe, and if this can prevent a larger outbreak in the pediatric population—and of course the adults that care for them and live with them—that is very important.”

The decision to provide the vaccine to children is “worth the potential risk,” she added.