Kids ages 5 to 11 should get a booster dose of Pfizer’s COVID-19 vaccine, advisers to the U.S. government said Thursday.

The Center for Disease Control and Prevention quickly adopted the panel’s recommendation, opening a third COVID-19 shot to healthy elementary-age kids — just like what is already recommended for everybody 12 and older.

The hope is that an extra shot will shore up protection for kids ages 5 to 11 as infections once again are on the rise.

“Vaccination with a primary series among this age group has lagged behind other age groups leaving them vulnerable to serious illness,” said CDC Director Dr. Rochelle Walensky, in a statement.

“We know that these vaccines are safe, and we must continue to increase the number of children who are protected,” she said.

Earlier this week, the Food and Drug Administration authorized Pfizer's kid-sized booster, to be offered at least five months after the youngsters' last shot.

The CDC takes the next step of recommending who actually needs vaccinations. Its advisers debated if all otherwise healthy 5- to 11-year-olds need an extra dose, especially since so many children were infected during the huge winter surge of the omicron variant.

But the U.S. now is averaging 100,000 new cases a day for the first time since February. And ultimately, the CDC's advisers pointed to growing evidence from older kids and adults that two primary vaccinations plus a booster are providing the best protection against the newest coronavirus variants.

“This always perhaps should have been a three-dose vaccine,” said Dr. Grace Lee of Stanford University, who chairs the CDC’s advisory panel.

The booster question isn't the hottest vaccine topic: Parents still are anxiously awaiting a chance to vaccinate kids under 5 — the only group not yet eligible in the U.S.

Dr. Doran Fink of the Food and Drug Administration said the agency is working “as rapidly as we can” to evaluate an application from vaccine maker Moderna, and is awaiting final data on the littlest kids from rival Pfizer. The FDA's own advisers are expected to publicly debate data from one or both companies next month.

For the 5- to 11-year-olds, it’s not clear how much booster demand there will be. Only about 30% of that age group have had the initial two Pfizer doses since vaccinations opened to them in November.

CDC adviser Dr. Helen Keipp Talbot of Vanderbilt University said health authorities must put more effort into getting youngsters their initial shots.

“That needs to be a priority,” she said.

Thursday's decision also means that 5- to 11-year-olds with severely weakened immune systems, who are supposed to get three initial shots, would be eligible for a fourth dose.

Pfizer and its partner BioNTech currently make the only COVID-19 vaccine available for children of any age in the U.S. Those ages 5 to 11 receive a dose that’s one-third the amount given to everyone 12 and older.

In a small study, Pfizer found a booster revved up those kids’ levels of virus-fighting antibodies — including those able to fight the super-contagious omicron variant — the same kind of jump adults get from an extra shot.

Vaccines may not always prevent milder infections, and the omicron variant proved especially able to slip past their defenses. But CDC cited data during the omicron surge that showed unvaccinated 5- to 11-year-olds had twice the rate of hospitalization as youngsters who got their first two doses.

Health authorities say for all ages, the vaccines are still offering strong protection against COVID-19's worst outcomes, especially after a third dose.

Some especially high-risk people, including those 50 and older, have been offered the choice of a second booster, or fourth shot — and the CDC on Thursday strengthened that recommendation, too, urging anyone who's eligible to go ahead and get the extra dose.

Still to be decided is whether everyone will need additional shots in the fall, possibly reformulated to offer better protection against newer coronavirus variants.