Explainer: Should you get a new COVID booster? If so, when?

John Wherry will wait until later in the fall to consider getting an updated COVID-19 boosterThe Penn immunologist knew it was too early for him to get his shot late this summer, especially since he wasn’t at high risk of contracting the virus.

It’s a calculation many Americans will face, as booster shots against currently circulating strains of omicron are available for people with widely different levels of risk and immunity.

Here are some things to know:

How is the new booster different?

They are combination or “bivalent” vaccines that contain half of the original vaccine used since December 2020, and half the protection against today’s major omicron versions, BA.4 and BA.5. This is the first update to the FDA-approved COVID-19 vaccine.

Who is eligible?

The updated lenses, made by Pfizer and its partner BioNTech, are licensed for use by anyone 12 and older, while rival Moderna’s version is meant for adults. They will be used as boosters for anyone who has already had a major vaccination series — using any US-approved company’s vaccine — no matter how many boosters they’ve already received.

If I just got an original booster, should I get the new one right away?

Do not. The FDA has set a minimum wait time of two months. But consultants at the Centers for Disease Control and Prevention say it’s better to wait a little longer. Some suggested at least three months, while another said people who were not at high risk could wait six months.

“If you wait a little longer, you’re going to get a better immune response,” said CDC consultant Dr. Sarah Long of Drexel University.

That’s because people who had recently received a booster already had more antiviral antibodies in their blood. Wherry, who was not involved in the government’s decision-making, explained that antibodies wear off over time, and a premature re-injection won’t provide much additional benefit.

What if I have recently recovered from COVID-19?

Even if you’re already infected, it’s still important to get vaccinated – but timing is also important here.

The CDC has long told people to hold off on getting vaccinated until they recover, but people may consider waiting three months after recovery to get vaccinated. Waiting three months is important, several CDC consultants said, both to get more benefit from the injection and to reduce the chance of a rare side effect (inflammation of the heart) that sometimes affects boys and young men.

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How much benefit will the new booster provide?

That’s unclear, as testing of this exact formulation has only just begun in humans.

FDA approves new booster Largely based on human studies of a similar tweaked vaccine that European regulators have just recommended. The tweaked shots target an early omicron strain, BA.1, that circulated last winter, and studies have found that they boost people’s antiviral antibodies.

With earlier versions of the omicron now replaced by BA.4 and BA.5, the FDA ordered additional tweaks to the injectables — tests in mice showed they elicited equally good immune responses.

There is no way to know whether antibodies produced by omicron-matched enhancers will persist for more than a few months. But the booster should also boost the immune system’s memory, increasing protection against severe disease from a constantly mutating virus.

How do we know they are safe?

The basic ingredients used in the two newer vaccines against omicron are the same.Pfizer and Moderna test targeted version of its BA.1 proves safe in human studies CDC consultants concluded that additional small recipe changes should make no difference.

Flu vaccines are updated every year and do not require human trials.

Can I get the new COVID-19 booster and flu shot at the same time?

Yes, one per arm.

What if I want to wait?

Encourage new boosters for people at high risk of COVID-19 when they expire. After all, BA.5 is still widespread, and hospitalizations among older adults have increased since the spring.

According to the CDC, most Americans who are eligible for an updated booster have had at least six months elapsed since their last injection—enough time for another injection should trigger a good immune response.

But the original formula is still very good at preventing serious illness and death, especially after the all-important first booster. So it’s not uncommon for young and healthy people to use a temporary jump in one shot as a time booster to prevent even mild infections, as Wherry did.

Wherry, a healthy 51-year-old, said he put off a second booster recommended for his age by seven months until late summer – just before international travel he knew would increase his exposure to people not wearing masks.

With the updated booster now available, he plans to assess in four or five months whether he’ll benefit from another shot when his antibody levels start to drop and he’s planning a holiday get-together.


The Associated Press Health and Science Division was supported by the Howard Hughes Medical Institute Division of Science Education. The Associated Press is solely responsible for all content.

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