Even if you already got your COVID-19 vaccine, you might soon need another one. Vaccine developers are already working on COVID-19 vaccine booster shots, which are meant to rev up your protection against the virus.
But some experts aren’t sure we’ll actually need them, even though the research that goes into figuring that out is necessary. Here’s what we know about COVID-19 vaccine boosters so far.
Why might we need booster shots?
A booster shot is intended to do what the name suggests: boost your immune response to a particular pathogen after an initial vaccine dose. “The additional dose ramps up the antibody response in your body,” Krutika Kuppalli, M.D., pandemic preparedness expert and assistant professor of medicine in the department of infectious diseases at the Medical University of South Carolina, tells SELF.
For instance, after you get your meningococcal conjugate vaccines at age 11 or 12, you should get a booster around age 16, SELF explained previously. And adults should get booster shots to protect against tetanus and diphtheria every 10 years or so. As with these other vaccines, a booster shot may increase your protection against COVID-19 by stimulating the production of additional antibodies, Dr. Kuppalli says.
There are essentially two scenarios in which a COVID-19 vaccine booster would be needed. First, you may need them to extend the protection after your immunity from the first COVID-19 vaccine you got wanes, like with 10-year tetanus boosters. Second, boosters may be necessary to expand protection against new variants of the coronavirus as it mutates.
Because the COVID-19 vaccines are relatively new, we don’t yet know how long protection from the initial vaccine doses will last. This is especially important to monitor because there have been a few cases in which people who’ve been infected with COVID-19 contract it a second time, Suman Das, Ph.D., an associate professor of medicine at Vanderbilt University Medical Center who studies the evolution of viruses, tells SELF.
So far, data suggests the body’s immune response to the initial vaccine regimen is strong and long-lasting. Pfizer and its partner BioNTech continue to monitor the effectiveness of their vaccine and reported in a press release that the vaccine is still 91% effective at preventing symptomatic COVID-19 infections six months after inoculation, just slightly reduced from the 95% achieved in clinical trials and 94% seen in real-world studies. But, ultimately, we’ll need to keep monitoring it to see how long that response lasts.
Boosters could be available as early as this fall or winter, according to statements from the CEOs of Pfizer and Moderna. While boosters will likely be offered for everyone, they may be more important for some parts of the population than others, Dr. Kuppalli said. For example, immunocompromised people may be at a higher risk and benefit more from an immunity boost.
New coronavirus variants will be an important factor.
There are reports of a few coronavirus variants that may be able to reduce the effectiveness of the current COVID-19 vaccines, so a booster shot could help address that by targeting those strains specifically.
New strains of SARS-CoV-2 arise naturally as the virus replicates. The virus does very little proofreading as it copies itself, so there’s likely to be a mistake known as a mutation, Dr. Das says. The more the virus spreads and replicates, the more mutations will be introduced. Not all of the mutations will be concerning, but it’s always a possibility that one of them will make it easier for the virus to escape the protection of the vaccine.
But a booster shot doesn’t necessarily have to be a new vaccine—it might just be a third shot of the original formula. For instance, in preliminary data from an ongoing clinical trial, Moderna said in a press release that it found that those who had received the initial two-shot vaccine still had antibodies six to eight months later. But, in about half of the 40 participants in the study, the existing antibodies were much less effective against new variants. After the researchers administered a third dose of the original vaccine, they saw a rapid increase in antibodies that were effective against the original virus as well as the B.1.351 and P.1, the variants that have been devastating to South Africa and Brazil, respectively.
Moderna also said its variant-specific booster, designed to combat the variant first detected in South Africa, was even more effective against newer variants. Moderna’s findings were published in a press release and have not yet been reviewed by other scientists. Pfizer and BioNTech have also begun a clinical trial testing two possible boosters: the original vaccine in a third shot and a variant-specific booster.
But researchers should pay careful attention to what’s happening in India, where there’s a severe COVID-19 crisis right now, says Dr. Das, whose lab is one of seven centers contracted by the CDC to sequence and identify new strains of SARS-CoV-2, the virus that causes COVID-19. Part of the issue in India is a coronavirus variant with two mutations that make it more contagious that’s circulating in some parts of the country. But because the virus “is spreading like wildfire” through such a large population there, that makes the probability of other concerning mutations much higher, Dr. Das says. Mutations that arise there—and already exist there—could have implications for vaccine developers working on variant-specific boosters here and globally.
The best thing you can do to protect yourself is still to get a vaccine now.
While staying ahead of variants and researching the potential for COVID-19 booster shots is important right now, “I’m not yet convinced we would need them,” Anna Wald, M.D. a professor in the department of epidemiology and head of the Allergy and Infectious Diseases Division at the University of Washington School of Medicine, tells SELF. Data so far shows that, even though the vaccines from Pfizer/BioNTech and Moderna are not as strong against some of the variants as the original virus, they ultimately do still provide significant protection against those variants. “Even though the virus has changed a little bit, the vaccine is still effective,” Dr. Wald says.
Plus, building whole new vaccines every time there’s a new worrying strain of COVID-19 isn’t a sustainable strategy, Dr. Kuppalli says. It’s “just playing whack-a-mole.” Not to mention, people may be less likely to comply with each additional shot they require, she says.
Ultimately, the best approach is to stop new variants and the worrying mutations they may contain from developing in the first place. And we do that by continuing to do the things we’ve been doing, including getting more people vaccinated.
“If you get the vaccine, it helps prevent the emergence of the variants,” Dr. Wald says, which might prevent the need for boosters altogether.