Finding out if you need a COVID-19 booster shot is like playing a risk game of your own choosing, with rules based on the initial shot you receive as well as your age, medical history, and your job.
Right now, boosters are recommended for anyone who has had a Johnson & Johnson/Janssen shot at least two months ago. Among those who initially received mRNA-based imaging performed by Pfizer-BioNTech and Moderna, boosters were available at least six months after the second dose for older adults, those with underlying medical conditions, and those living or working in high-exposure environments, such as long-term care facilities. Pfizer on November 9 asked the US Food and Drug Administration to authorize the booster for all adults, but the agency has yet to do so.
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To complicate matters further, the US Centers for Disease Control and Prevention says that eligible people can get a boost with any of the three vaccines currently available, regardless of which type they inject for the first time. This approach is called “mix and match”.
But what are the pros and cons of branching versus maintaining brand loyalty?
It’s too early to say. To date, only one combination study of the vaccines is available in the United States. It is not designed to find the “best” vaccine combination, but rather to test the overall safety and effectiveness of mixing and matching. In that respect, the results have been clear: mixing and matching produces an immune response that is as safe as or stronger than the one produced by an additional dose of your original injection. But because the study wasn’t intended to compare different combinations, it’s difficult to recommend one type of booster over another.
The data showed that people who were initially injected with Johnson & Johnson produced more antibodies when they were boosted with a single dose of Pfizer-BioNTech or Moderna, rather than a second dose of Johnson & Johnson.
But even that outcome is not as straightforward as it seems, said Dr. Mohammad Sobhanie, an infectious disease physician at Ohio State University Wexner Medical Center. “Antibodies are only part of immunity, so ‘does a stronger antibody response mean it’s a better vaccine’,” Sobhanie said.
However, based on what is known to date, Jason Pogue, clinical pharmacist of infectious diseases at Michigan Medicine, recommends mRNA boosters for anyone with Johnson & Johnson disease for the first time. “I think the data support that you get a stronger and broader response with the mRNA vaccine,” Pogue said. (Pfizer-BioNTech or Moderna are fine, he added.)
For people just starting out with the two-dose vaccine, Pogue says the choice of booster shot is a little less important. “If you feel more comfortable getting what you got the first time, then go ahead and start it,” he says. But if that shot isn’t in stock when you go to the pharmacy, it’s “perfectly reasonable to buy the ready-made one.”
If you’re not sure which booster to take, Sobhanie recommends talking to your doctor, who can consider your specific circumstances. Although serious side effects from vaccination are very rare, a very small number of women under the age of 50 have developed serious blood clots after receiving Johnson & Johnson vaccine, while in rare cases Recently, mRNA-based vaccines have been linked to heart problems in young people, especially young men and teenage boys. If you’re in one of those demographics, your doctor may recommend that you choose another shot for your booster shot, just to be on the safe side.
And, of course, if you haven’t been vaccinated, it’s a very good idea to do so. The initial shots are still working well to prevent serious illness and death. Boosters are just another way to protect vulnerable people.
A version of this story originally appeared in the Coronavirus Brief.
