(NEXSTAR) – As COVID cases caused by the omicron variant finally start to wane in the U.S., is it time to look ahead to the next variant? And will we need another booster shot to protect us from it?

It’s too soon to determine whether a fourth vaccine dose (or a third dose for the Johnson & Johnson recipients) will be necessary for everyone, the experts we asked said. It’s an answer they acknowledge is frustrating for those concerned about the ever-evolving coronavirus. But there are some things we know about who needs that extra protection now, and what we might expect next.

Who needs a fourth dose now?

The Centers for Disease Control and Prevention recommend some moderately and severely immunocompromised people 12 and older should get three primary shots of an mRNA vaccine (either Pfizer or Moderna) plus a fourth shot as their booster.

The timing and type of vaccine depend on your age group and when you last received a dose. Check the CDC’s guidelines or talk to your doctor to see if a fourth shot is recommended for you.

Right now, this is the only group recommended to get a fourth shot by the CDC, but that’s caused some confusion for people – and providers.

“We get a lot of complaints from people now that are eligible for their fourth dose that they’re getting pushback from CVS and Walgreens and they’re all being told no cause for a fourth dose,” said Dr. Jim Conway, who heads the University of Wisconsin’s immunization program.

Who might need the fourth dose next?

Israel recently started offering fourth shots to everyone 60 and older, but the early data hasn’t yet convinced many American doctors it’s time to do the same here.

Dr. Bob Wachter, chair of medicine of the University of California, San Francisco’s medical school, concluded a thorough Twitter thread examining the data out of Israel by saying, “Personally, if I was offered a 4th shot today, I’d hold off. But if additional data confirm the Israeli findings, then I’d probably take it, because the risks are near-zero and the benefit may grow over time.”

Conway said he wouldn’t be surprised if those 65 and older become the next group recommended to get another shot.

“I think everybody is well aware those two populations, immune-compromised and over-65s, need special attention and I will not be surprised at all if we end up in a situation where they get different recommendations,” he said.

If deemed necessary, the types of boosters older Americans get may change, too. They could be super-charged boosters (such as a full dose of Moderna instead of the half dose being used as a booster now) or they may need doses more frequently, Conway said. Either way, the goal would be to maintain higher levels of antibodies in the more vulnerable elderly population.

Will the general population need another shot soon?

This is the biggest remaining question.

Dr. Anthony Fauci, the country’s top infectious disease doctor, told ABC News it’s “entirely conceivable” we could need another booster down the line. But doctors say there’s so much that remains to be seen.

“It’s too early to be asking about a fourth shot in the U.S. outside of the immunocompromised populations,” said Dr. Peter Chin-Hong, an infectious disease expert at UCSF. “The fourth shot data has not been promising so far in adding any benefit beyond three shots.”

“That’s still the process we’re in right now is [we are] still mapping out the duration of the immunity and how good the immunity is against what’s circulating in front of our very eyes,” Conway said.

With the dominant variant circulating now, people who are fully vaccinated and boosted are still very well protected from serious illness, he said.

Instead of worrying about a fourth shot just yet, he reminded everyone who is eligible to get a third shot. Only 26% of Americans are fully vaccinated and boosted, according to data analyzed by the New York Times.

“Everyone over 12 needs a booster now as soon as they’re eligible to be able to maintain omicron immunity,” Conway said.

In the future, Chin-Hong also said a fourth shot could be recommended “to prevent any infection that may lead to workforce disruptions like in health care. But three may be the magic number of shots that keeps most of us away from the hospital for many years even if we can get breakthrough infection in the future.”

What about the J&J folks? How protected are they?

Folks who received the Johnson & Johnson vaccine for their original dose and then received a booster shot aren’t particularly well studied, said Conway.

First of all, they had three choices for a booster shot: a second J&J dose, a full Pfizer dose or half a Moderna dose. Each case results in different levels of protection.

Conway estimated someone who has received a J&J plus one of the mRNA vaccines is likely a bit better protected than someone who received two mRNA doses, but less protected than someone who has received three.

Will J&J recipients need a third dose sooner than others?

“I won’t be surprised if they do get a recommendation ultimately, but they’re probably going to need real data that there’s increasing breakthrough cases in that population that are out of proportion to the other vaccines. And so far we haven’t seen that data yet supports the need for another dose,” Conway said.

Will we need booster shots tailored to specific variants?

When asked this question, Conway responded: “It’s totally a wait and see situation.”

“Right now, there’s plenty of evidence that the original vaccine strains hold up really well and as long as you get boosted, that’s all you need to neutralize omicron well enough,” he elaborated. “But I think nobody knows or trusts this virus so you just don’t know when a big enough shift in the genetics happens and suddenly your existing vaccine protection doesn’t hold up anymore.”

The vaccine manufacturers are working on developing an omicron-specific vaccine right now in part to lay the groundwork for future variants, if added protection is needed. “It’s important to do it in case you need to be able to do it,” Conway said.

As long as the virus is circulating somewhere in the world, it will continue to mutate.

“There’s currently no evidence that we need additional boosters in the majority of population nor is there evidence we need specific viral boosters for new variants. But boy, I’m not going to be surprised if that happens,” Conway said.