How to Decide If It's Time for Your Second Booster

It's available for people over 50 and those who are immunocompromised. But while some may want to get boosted soon, others can wait, the CDC says.

A vial of the Pfizer-BioNTech Covid-19 vaccine on a blue background Photo: Hannah Beier/Getty Images

Since March 29, people 50 and older as well as some younger people who are immunocompromised have been able to get a second booster dose of the Moderna or Pfizer-BioNTech vaccine. People who were initially vaccinated with the one-shot Johnson & Johnson vaccine and then received a booster dose of Johnson & Johnson are also eligible for a second booster.

But many people have not gotten even a first booster shot, which all Americans 12 and older have been eligible for since early January. And uptake on second boosters shots has been even slower.

As of April 26, about 100 million people had a first booster dose. And by April 19, just 4.3 million people had received a second booster, according to data presented at an April 20 meeting of a Centers for Disease Control and Prevention vaccine advisory group.

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With each additional vaccine dose authorized, there has been less uptake, says Gregory Poland, MD, director of the Vaccine Research Group at the Mayo Clinic in Rochester, Minn. But people may also be holding off on a fourth dose because it’s not yet clear they should get it yet.

Among people eligible for a second booster based on age, 11 percent have already received a second booster, and 42 percent say they are very likely to do so, according to a nationally representative CR survey of 2,224 U.S. adult residents that was administered from April 7 to April 18 (PDF link).

Anyone who is eligible for a first booster dose should get one, according to the CDC. There’s a significant amount of research showing that boosters lower the risk of infection, serious disease, hospitalization, and death. 

But the recommendation for a second booster dose is not yet as strong. The CDC acknowledges that some people may want to get one as soon as possible, while others may want to wait longer. The agency’s recommendation says that eligible people can choose to get a second booster, but it does not yet say that people “should” get one. 

To help clear up some of the confusion about who should get the second booster sooner, the CDC has offered some guidance.

Why and When to Get a Second Booster Dose

The reason to get a second booster is similar to the reason to get a first: There’s evidence that after a certain amount of time, protection provided by vaccination or prior infection wanes. Two months after a first booster shot, vaccine efficacy against an emergency room or urgent care visit was 87 percent, and efficacy against hospitalization was 91 percent, according to a study released by the CDC on Feb. 11. But four months after that shot, efficacy against hospitalization fell to 78 percent.

Data from Israel during the omicron surge shows that people 60 or older who got a second booster dose had a 78 percent lower risk of death than people who just got one booster, though the absolute risk of death from COVID-19 remains small for anyone who got a booster in the first place, Poland says.

The difficult part about deciding when to get a second booster is that even that extra protection wanes, too. According to an April 6 study published in The New England Journal of Medicine, protection against any infection starts to wane about a month after the fourth dose, though the additional protection against severe disease lasts at least six weeks.

Because of that, “the best time to get this booster would be two weeks before you get infected,” Poland says. And while it’s not exactly possible to determine when that might happen, your own health status, the current risk in your community, and potential risks you may be exposed to in the future can help you figure out when you should go ahead and get that shot, he says.

First off, you need to be eligible for a fourth shot. Anyone who is at least 50 years old or at least 12 years old and moderately or severely immunocompromised is eligible, as long as they got their first booster at least four months prior. People who were initially vaccinated with the one-shot Johnson & Johnson vaccine are also eligible for a second booster dose with either the Moderna or Pfizer-BioNTech vaccine if they fall into those same eligibility groups or if their first booster dose was with the J&J vaccine. 

Among eligible people, the CDC is encouraging people at the highest risk for severe COVID-19 who have not recently had COVID-19 to go ahead and get a second boost as soon as they can, the agency’s director, Rochelle Walensky, MD, said on an April 26 press call. 

That may be especially important because there is currently an ongoing surge in cases related to subvariants of the omicron strain of the coronavirus, including BA.2, which could increase the risk of infection for many now or in the coming weeks. “There are areas in the country, particularly in the Northeast, where we are seeing a higher number of cases, and we’re starting to see some hospitalizations tick up,” Walensky said. “This is something we need to watch carefully.”

People who should get their second boost sooner include those who have medical conditions that put them at higher risk for severe COVID-19, and people who are older. By the time people are in their 70s, immune system protection weakens, Poland says. Those who live or work in communities where the risk for COVID-19 is higher may also want to consider getting the booster sooner, as well as those at increased risk for getting the coronavirus because of work, their living situation, travel, or planned gatherings, according to the CDC.

But for now, the CDC says, other eligible people can wait. The agency says that people who have had COVID-19 in the past three months may want to consider waiting, for example. It also notes that getting a second booster may be more important in the fall of 2022, when many public health officials expect another surge in cases.

Poland, who has consulted with a number of manufacturers on the development of their vaccines, says it’s likely they will have a booster targeting specific variants of the coronavirus available by late summer or early fall. The CDC acknowledges that some people may want to wait for that. And even if people get boosted now, they may need to get a booster targeting a specific variant then, Poland says.

It’s not yet clear whether we’ll need annual boosters, as many vaccine manufacturers have suggested. But if getting a booster now would discourage someone from getting a booster in the fall when one is likely to be recommended, and they aren’t at particularly high risk, the CDC says they could consider waiting.

Head shot image of CRO Health editor Kevin Loria

Kevin Loria

I'm a science journalist who writes about health for Consumer Reports. I'm interested in finding the ways that people can transform their health for the better and in calling out the systems, companies, and policies that expose patients to unnecessary harm. As a dad, I spend most of my free time trying to keep up with a toddler, but I also enjoy exploring the outdoors whenever possible. Follow me on Twitter (@kevloria).