What to Know About the Bivalent Booster Shots

The current available boosters target the Omicron subvariants BA.4 and BA.5, which are no longer dominant. Here’s what experts say about who should get them and how well they still work.

The bivalent booster shots target the Omicron subvariant BA.5.
Credit...Charity Rachelle for The New York Times

The Centers for Disease Control and Prevention greenlit a new tool in September for battling the pandemic: updated booster shots.

The bivalent booster shots were designed to target the Omicron subvariants BA.4 and BA.5, which were previously the dominant version of the virus. Since then, two new subvariants, BQ.1 and BQ.1.1, have become dominant. But there is still a benefit to getting the bivalent booster. Here’s what you need to know.

The bivalent vaccine is available at pharmacies 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.

The C.D.C. has recommended the Pfizer-BioNTech bivalent booster for anyone 5 years old or older if it has been at least two months since the person’s last vaccination or booster shot. People 6 years old or older can get the Moderna bivalent booster or the Pfizer booster if it has been at least two months since their last vaccination or booster. Children between the ages of six months and five years old who previously received a primary series of Moderna vaccines can get a Moderna bivalent booster if it has been at least two months since they completed their primary series. Children six months old through four years old who are currently getting their Pfizer vaccine series will receive the Pfizer bivalent booster as their third dose. Children six months old through four years old who have already finished their three-dose series with the Pfizer vaccine cannot currently get a bivalent booster dose.

If you have questions or concerns about your eligibility or your child’s eligibility, consult your primary care doctor.

The booster 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 F.D.A. no longer authorizes the previous Pfizer and Moderna boosters, but the C.D.C. has allowed adults 18 and older to receive a monovalent Novavax booster. You can get the Novavax booster instead of the new bivalent shots if you have not received any other booster.

People who have not received their first doses of the vaccine will still receive the original vaccines that were rolled out in late 2020.

The F.D.A. authorized the bivalent 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 that same two-month interval between doses, although several members voiced concerns that it 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, said Aubree Gordon, an epidemiologist at the University of Michigan. “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.”

Once you do get the booster, it typically takes around one to two weeks after you get the shot for your antibodies to “kick in,” Dr. Gordon said.

Yes. Booster shots are safe for pregnant people, Dr. Chin-Hong said, and just as with the initial vaccines, scientists expect that the antibodies a pregnant person generates could transfer to the baby once it’s born.

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.

Emerging data indicates that the bivalent boosters may not provide strong protection against breakthrough infections, especially as the new subvariants BQ.1 and BQ.1.1 have edged out BA.4 and BA.5 and are now dominant. But the boosters continue to help protect against severe disease, said Dr. Justin Fiala, a pulmonary and critical care specialist at Northwestern Medicine.

“It still provides more protection than the original vaccine,” Dr. Chin-Hong said. “People still continue to say, ‘It doesn’t work.’ But that’s missing the point of serious disease, hospitalization and death.”

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, said Shane Crotty, a virologist at the La Jolla Institute for Immunology, adding, “It’s really up to the virus.”