86% of kids under 17 have antibodies from a past COVID infection, CDC data shows

More than eight in 10 kids under the age of 17 have antibodies from a past COVID-19 infection, according to new data from the Centers for Disease Control and Prevention.

The analysis shows that as of August, 86% of children between 6 months and 17-years-old have had at least one COVID infection since the pandemic began.

That number is an increase from data in April, when the public health agency found 75% of people under the age of 17 had been infected with the virus.

"What we have to recognize is this is more of an indication that there's been broad spread of this virus in the pediatric community," said Dr. John Brownstein, an ABC News contributor and chief innovation officer at Boston Children's Hospital. "And that, you know, the kids are not sheltered from this virus. And we know that in a small number of cases, there's severe impacts."

What the findings don't mean is that 86% of children and adolescents are now protected against COVID reinfection because they've had COVID before. Experts have noted that they don't know exactly how long protection from infection lasts after contracting the virus.

"What we should not take away from this data is that that the kids are now immune from infection, so we can't make the leap that continual investment in vaccines and protections of our kids is not important," Brownstein said. "As we know, immunity wanes, variants evolved to evade prior immunity and so, you know, this is more a reflection of how amazingly widespread this virus is but it's not a reflection of future risk."

One ABC News analysis of state data found that, as of June, there'd been more than 1.6 million reinfections across 24 states, but experts said the number was likely much higher.

The CDC recommends everyone, regardless of prior infections, stay up to date on vaccinations -- including the newest booster shot, which targets the currently circulating BA.4 and 5 variant.

The agency recommends people ages 12 and older to receive one updated booster at least two months after their last vaccine dose. Boosters are also available for kids ages 5 through 11, but only if they received the Pfizer-BioNTech primary vaccine series.

The booster for that age group targets the original virus strain, not variants, but the CDC has said it expects vaccine boosters designed to target variants like omicron to be available for children aged 5-11 years by mid-October.

And Dr. Peter Marks, the FDA's vaccine chief, said in late September he was "confident that we're only a matter of weeks away" from authorizing new boosters for the 5-11 age range. For kids under 5, Marks said there were still "a few months away" from authorization.

In the meantime, Marks encouraged parents to make sure their children get the primary vaccine series.

"There are a lot of kids ages 5 to 11 out there who haven't had their primary series, so you can't get the updated booster until you've had the primary series. So it's a good idea to think about getting your child vaccinated against COVID-19," he said.

- ABC News' Alexandra Hutzler contributed to this report.