The United States is launching a new distribution program for Covid-19 booster shots — and if you're one of the nearly 14 million people who got the one-shot Johnson & Johnson vaccine, you probably have a few questions.

On Wednesday, top U.S. health officials — including CDC Director Dr. Rochelle Walensky and White House chief medical advisor Dr. Anthony Fauci — said booster shots will become available next month, citing data suggesting that vaccine-induced protection from the virus wanes over time. People who received two doses of an mRNA vaccine from Pfizer or Moderna are now eligible for a booster shot eight months after their last dose. Notably absent: a recommendation for anyone who received the J&J vaccine.

More data on whether or not J&J recipients will need boosters — and if so, what kind of vaccine — is expected in the coming weeks. "With those data in hand, we will keep the public informed with a timely plan for J&J booster shots as well," the U.S. Department of Health and Human Services said in a statement Wednesday.

But with Covid's delta variant surging, J&J recipients may feel a sense of urgency, and a need for answers sooner rather than later. Conflicting information is already running rampant: While the U.S. Food and Drug Administration is expected to evaluate the efficacy of a second J&J shot later this month, some infectious disease experts are already recommending a booster shot from one of the two approved mRNA vaccines.

"Patients cannot wait for perfect data," Dr. Leana Wen, an emergency physician and public health professor at George Washington University, tells CNBC Make It. "People who need additional protection now need to be given the option."

If you got the J&J vaccine and are wondering what to do, here's what experts want you to know:

Should you try and find a mRNA vaccine if you got J&J?

Just because you can seek out another vaccine doesn't necessarily mean you should at this stage.

Determining whether or not you need a Covid booster is "a complex decision that takes into account your medical history, your family circumstances and who you live with, your Covid-19 exposures, as well as your risk tolerance," Wen says. An mRNA booster shot, for example, could lead to stronger side effects for some people, compared to their initial vaccinations. You should talk to your clinician or primary care doctor about your own personal circumstances before doing anything, Wen notes.

Some people may already be jumping the gun. CDC data indicates that millions of people went ahead and received an additional dose of Covid vaccine, "through some finagling of the system," despite the official recommendation, says Dr. William Schaffner, a professor of infectious diseases at the Nashville-based Vanderbilt University Medical Center. "Some of those undoubtedly are J&J vaccine recipients."

In San Francisco, it's already above-board: J&J recipients can request to get a supplemental dose of an mRNA vaccine.

The FDA is expected to grant full approval for the Pfizer and Moderna vaccines this fall, though the exact timeline is unclear. That would allow physicians and healthcare providers to prescribe mRNA boosters for people with immunocompromising health conditions, a potential boon for many who got the J&J shot. "That is really what needs to happen in this case: Clinicians need to be able to exercise their judgment in order to recommend what is best for their patients," Wen says.

How other countries are handling mix-and-match boosters

The J&J vaccine is a viral vector vaccine, which works by using a harmless version of a different virus, called a "vector," to deliver information to the body that helps it protect you, according to the CDC. That makes it very similar to the AstraZeneca/Oxford vaccine, which is currently in use in Europe, the United Kingdom and Brazil — but not yet approved in the U.S.

Some countries, such as Germany and the U.K., are routinely giving doses of mRNA vaccines to people who got the AstraZeneca vaccine, Schaffner says, noting that the method seems to be working well with few side effects.

Wen suggests the U.S. will eventually move in a similar direction. "With evidence from other countries about the success of the mix-and-match approach with the AstraZeneca vaccine and Pfizer, it would seem very reasonable for there to be guidance for people who've got the J&J vaccine to get an mRNA booster at this time," she says.

The reason why there's no clear guidance for J&J recipients in the U.S. yet: timing. The mRNA vaccines from Pfizer and Moderna, which use genetic material to teach your cells how to make copies of the coronavirus' spike protein, were greenlit in December 2020 — giving researchers a head start on gathering data about how long protection lasts. The J&J vaccine, on the other hand, only received emergency use authorization in March 2021.

Ultimately, the CDC's Advisory Committee on Immunization Practices has to make a formal recommendation before Americans can consider following suit. "They have not been, what I would call, embracing of the European experience in helping inform what they do," Schaffner says. "Which is not to say they won't do that in the future. They've just been kind of sticklers."

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