There are more than 5 million known COVID-19 cases in the U.S. right now, according to Johns Hopkins University.

One group in particular, children, is seeing a noticeable rise in U.S. infections.

Public health officials warned about opening schools in states with COVID-19 hot spots, but others want students back in class. "For the most part, they do very well. I mean, they don't get very sick. They don't catch it easily. They don't get very sick," says President Donald Trump. "In terms of risks to school kids, this is lower risk than seasonal influenza," says Florida Gov. Ron DeSantis (R).

However, medical experts say having youths in crowded hallways and classrooms poses a significant threat. "You're waiting for a second fire to erupt. You're pouring fuel on a raging fire," says William Haseltine, former professor at Harvard Medical School.

More than 800 students in Georgia's Cherokee County are in quarantine due to possible coronavirus exposure, just one week after in-person learning began. "We are not out of the woods yet and we cannot take our foot off the gas. I'm asking that all Georgians continue to remain vigilant as we continue this fight," says Georgia Gov. Brian Kemp (R).

Over the past four weeks, there's been a 90% hike in known COVID-19 cases among U.S. children, according to the American Academy of Pediatrics and the Children's Hospital Association. "We think we're going to see an explosion of cases in September that will far surpass what we saw after Memorial Day, and this is just going to continue increasing, getting higher and higher in terms of numbers," says Michael Osterholm, director at the Center for Infectious Disease Research and Policy.