What's more, new versions of the vaccines are in the works that aim to specifically target the omicron subvariants BA.4 and BA.5. But those shots aren’t expected until this fall — leading to questions about whether people should get boosters now, or simply wait.

Here's what to know about Covid boosters.

Who can get a booster now?

Adults ages 50 and above are strongly encouraged to get two booster shots.

Those who were initially vaccinated with one of the mRNA vaccines can get the first booster five months later and the second four months after that.

Those 50 and above who originally received the Johnson & Johnson shot can get their first boosters at least two months after the first dose and a second booster four months later. Both boosters should be from either Pfizer-BioNTech or Moderna.

Older adults have had a higher risk for Covid complications since the beginning of the pandemic. The Biden administration is urging those 50 and older in particular to sign up for boosters.

The director of the Centers for Disease Control and Prevention, Dr. Rochelle Walensky, said at Tuesday’s briefing that people ages 50 and above who've had only one booster shot have four times the risk of dying from Covid, compared to those in the same age group who've had two booster doses.

Adults ages 18 to 49 are eligible for one booster dose, or a third shot overall, at least five months after their initial series of vaccinations with either the Moderna or the Pfizer vaccine.

Children and teenagers ages 5 to 17 can get boosters as long as it has been at least five months since their first two Pfizer doses. Children who initially received the Moderna shots don’t yet qualify for boosters.

Children ages 6 months though age 4 are eligible for the initial rounds of either Pfizer’s or Moderna’s vaccines; however, boosters aren’t yet recommended for that age group, according to the CDC.

General guidance is that people ages 5 and up with weakened immune systems can get additional shots sooner than the general population, often three months after their first rounds of vaccinations.

Do the current boosters work against BA.4 and BA.5?

The current shots were designed to address the original strain of the coronavirus. But as the virus has mutated, it has become more and more adept at sneaking past the wall of immunity our bodies have built up — through previous infection, vaccination or both.

Right now, omicron subvariants BA.4 and BA.5 account for more than 80% of cases circulating. Experts say the current shots don’t prevent infection from BA.4 and BA.5 as well. Indeed, breakthrough infections and reinfections are reported regularly.

Experts say the shots can, however, reduce the risk an infected person will develop complications of the virus.

"If you're eligible for a booster shot, you should get it," said Dr. Jorge Salinas, an epidemiologist and infectious diseases expert at Stanford University. "Even if it fails to fully protect you against getting infected, it can still be the difference between a mild or severe infection."

If I get a booster now, can I get another shot this fall?

Dr. Robert Hopkins, the director of internal medicine at the University of Arkansas for Medical Sciences in Little Rock, said he got about a half-dozen calls from people asking that very question one recent morning.

He advises his patients and even colleagues who have queried him on the matter to get the booster now if they’re eligible, because the new vaccines are, at best, at least four months away from public rollout.

"We don't lose anything by getting vaccinated or boosted now," Hopkins said. "And we certainly gain protection."

The White House Covid-19 response coordinator, Dr. Ashish Jha, echoed the advice at Tuesday's briefing. "Getting vaccinated now will not preclude you from getting a variant-specific vaccine later this fall or winter.

"This is not a trade-off," he said.

I just had Covid. Do I need a booster?

Yes, as long as you've recovered from the acute illness, meaning you are fever-free and back to normal daily activities, said Dr. William Schaffner, an infectious diseases expert at Vanderbilt University Medical Center in Nashville, Tennessee. That includes diagnoses within the past month, he said.

"There is no downside" to getting the booster after infection if you are eligible, he said. "It turns out that people who’ve recovered from Covid and then get a booster have the highest levels of antibody."

Walensky said she has seen "large amounts of data that have demonstrated that if you've previously been infected and you also get vaccinated, you have much more protection than prior infection alone."

Should kids get boosters before school starts?

Pediatricians do encourage parents to get their kids booster shots before they head back to school if they haven’t been boosted already — even if new vaccines are, indeed, available in the coming months.

"It may be that this fall, the recommendation changes and there's a new booster, but in the meantime, your child will have the maximal amount of protection possible from our current vaccines," said Dr. Richard Besser, a pediatrician who is the president of the Robert Wood Johnson Foundation.

"That's important, because the pandemic isn't over," he said.

Rarely, heart inflammation has been reported following Covid vaccination, especially among young men. But studies have shown that such inflammation, called myocarditis, is far more common following Covid infection than vaccination.

While it's true that children have largely been spared the most severe consequences of Covid, their risk isn’t zero.

Besser said the fact that millions of children have had the vaccines should reassure parents.

"There is now much more safety data that should make parents feel much more comfortable about the safety and effectiveness of vaccines," he said.