What to Know About the New Booster Shots

"New shots targeting the latest version of the Omicron variant will be available soon. When should you get yours? Here’s what experts recommend.

With fall and winter looming, along with an anticipated seasonal surge in Covid cases, the Centers for Disease Control and Prevention greenlit a new tool for battling the pandemic: updated booster shots. The Food and Drug Administration authorized the shots earlier this week.

The new shots target the Omicron subvariant BA.5, the dominant version of the virus. Here’s what you need to know.

When will new boosters be available?

The updated boosters could roll out within days.

It typically takes around one to two weeks after you get the shot for your antibodies to “kick in,” Aubree Gordon, an epidemiologist at the University of Michigan, said.

Where can I get the new booster shot?

The new vaccine will most likely be available at pharmacies, doctors’ offices and community health centers. Many mass-vaccination clinics across the country have closed, so you may have to seek out a new vaccination site. You can search a directory of sites at vaccines.gov.

Who is eligible?

The F.D.A. authorized the Pfizer-BioNTech booster for anyone 12 or older who received an initial vaccination or booster shot at least two months ago. Adults 18 or older can get the Moderna vaccine if it has been at least two months since their last vaccination. The C.D.C. recommended the same eligibility guidelines as the F.D.A.

What is the difference between the Pfizer and Moderna boosters?

Beyond the difference in age criteria, there is no practical difference between shots, said Dr. Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco. “From your body’s immune system perspective, it doesn’t remember which brand it is,” he said.

Will this Omicron-specific booster entirely replace the other boosters?

The new booster shot is a bivalent vaccine, meaning that it targets two versions of the coronavirus: the original strain, and the Omicron subvariants BA.4 and BA.5. The previous booster shot targeted only the original version of the virus.

The new shots will most likely become the only available boosters. The F.D.A. no longer authorizes the previous booster doses for people in the approved age groups. People who have not received their first doses of the vaccine will still receive the original vaccines that were rolled out in late 2020.

How long should I wait to get the new booster if I recently had a shot or got Covid?

The F.D.A. authorized the updated boosters for people who were at least two months out from their last shot (whether that was the original vaccine or a booster), but you might want to wait longer. An advisory panel to the C.D.C. voted to recommend the same interval between doses, although several members voiced concerns that two months was too short.

Doctors and immunologists said that in general, people should wait around four to six months after immunization or infection.

That’s because your body will probably not generate much of an immune response so soon after a previous encounter with the virus, Dr. Gordon said. “Your immunity level is so high that you’ll just neutralize immediately the antigen that’s being produced — you kind of reach a ceiling,” she said. “You don’t have that much higher to go.”

Does the new booster offer better protection than past ones?

The previous booster shots provided robust protection against severe disease. There were, however, people who had breakthrough infections even shortly after receiving booster shots, including President Biden.

Doctors expect the newest iteration of boosters to offer more protection against breakthrough infections, but they won’t be bulletproof. “It’s not a game-changer,” Shane Crotty, a virologist at the La Jolla Institute for Immunology, said. “But it is going to be better.”

There is not yet real-world data on how these bivalent vaccines perform in humans. Infectious disease experts compared the process of creating the new boosters to that of the annual flu shot, which is updated each year and primarily tested on animals, not humans.

“I’m not worried at all,” Dr. Chin-Hong said. “They’re not using any new ingredients. It’s like you’re still making brownies — you’re still using chocolate, sugar, flour. Maybe now you’re using more chocolate.”

Will there be more boosters in the future?

It’s unclear whether this will be the last Covid booster offered, or whether there will be new boosters on a regular basis. The United States could offer the vaccine each year around the fall, similar to the flu vaccine, if the virus surges become predictable, Dr. Chin-Hong said.

But the pandemic’s trajectory has been anything but straightforward, and it’s hard to anticipate the state of the virus over the next few months, let alone the next few years. If the virus had not evolved, we probably would not need any new shots now, Dr. Crotty said, adding, “It’s really up to the virus.””