CNN  — 

Covid-19 cases are on the rise among kids in the United States as another school year gets underway.

New cases reported among children in the last week of August were 14% higher than they were two weeks earlier, according to data tracked by the American Academy of Pediatrics. They jumped even more in the South, where classes have been in session for weeks. In contrast, overall cases for all ages were down about 17% in the same timeframe.

Experts say that this increased transmission is to be expected – but that keeping kids in school should be the priority, and there are now enough ways to make sure it’s done safely.

“We do see infectious diseases spread every time the school year starts. That’s been a phenomenon well-known long before Covid,” said Dr. Sean O’Leary, chair of the pediatric association’s committee on infectious diseases. “The good news is, we’re in a much different place with this pandemic than we were two years ago, or even last year, in terms of the percentage of the population that’s vaccinated.”

Eligibility for Covid-19 vaccines was expanded to include ages 5 to 11 in November, making this the first full school year in which all school-age children could have their initial series.

Still, vaccination rates for children lag and have changed little recently: About 61% of children ages 12 to 17 and just 31% of children 5 to 11 have their initial series, compared with about 77% of adults, according to data from the US Centers for Disease Control and Prevention.

Children 5 and up are also eligible for a booster shot, but only those 12 and up can get the updated version. And so far, only about 10% of children ages 5 to 17 have gotten a booster.

The slow rollout of vaccines for children is part of why pediatric cases became more prevalent during last school year, said Dr. Grace Lee, pediatrics professor at Stanford University School of Medicine and chair of the CDC’s vaccine advisory committee.

In 2020, there wasn’t much virus circulating among children because most were learning from home, she said. But the negative effects of remote learning were coming into focus.

An assessment conducted by the National Center for Education Statistics found that test scores among 9-year-olds plummeted in math and reading after the pandemic. And mental health-related visits to emergency rooms among adolescents saw a steep increase.

“We needed the kids to go back in person for learning. At the same time, we didn’t have as many opportunities to offer vaccination in a timely manner to those who were going back to school. So that is really challenging,” Lee said. “Part of the reason we saw case rates jump up in pediatrics is because they were the last population to get vaccinated.”

Now, though, there’s greater population immunity built up through a combination of vaccination and infection.

About 4 out of 5 children in the US have had Covid-19 at some point, according to estimates from the CDC that are based on the presence of antibodies in blood samples. This is a significant jump from the end of 2021, when 45% of children were estimated to have had Covid-19.

That doesn’t mean the potential for Covid to spread in schools should be ignored, experts say; it was still a top 10 cause of death for children last year, and there’s too much uncertainty about what’s to come.

“We’ve now been infected, vaccinated, infected, vaccinated. Where are we going this season? I do think that we have to take it one year, one month at a time,” Lee said.

Last year, the CDC updated its school guidance to prioritize in-person learning while maintaining layered prevention strategies such as masking, physical distancing and vaccinations for those who were eligible. Last month, the guidance was updated again, dropping recommendations for programs that require a negative test to stay in the classroom or restrict kids to one classroom, or cohort.

Mask mandates have dropped across the county, too.

However, while the CDC and others are more generally focused on preventing severe disease from Covid-19, experts say there are still benefits to avoiding infection, especially for kids in school.

“We have to really take a life course approach with children,” Lee said, thinking about both the short- and long-term effects.

In the short term, a Covid-19 infection “completely disrupts your family life and your school life and your personal life,” she said.

“Every time someone gets sick – whether it’s Covid or flu or anything else – they’re getting further and further behind,” she said. And “the burden of infection is not equitable,” causing disparities to grow.

Children can have long Covid, too – a direct long-term risk of infection. And if enough teachers get sick, the indirect risks from the early days of school closures can resurface.

Get CNN Health's weekly newsletter

Sign up here to get The Results Are In with Dr. Sanjay Gupta every Tuesday from the CNN Health team.

As a parent herself, Lee recommends that kids continue to wear masks in schools and keep up-to-date with any vaccines they’re eligible for.

“I would say kids have been the most adaptable during the pandemic. So I’m less worried about that piece of it,” Lee said.

“My hope is that we make schools a safe and equitable place to continue to learn and that we support our children, no matter what happens.”