The Real Benefits of Annual Covid-19 Booster Shots
Peter Hotez has made every effort to stay up to date with Covid-19 vaccines, starting with the initial two doses and continuing through each booster iteration. “I’ve gotten every one possible,” he said.
Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, has followed the guidance from the Centers for Disease Control and Prevention, which currently recommends annual shots for everyone over six months of age. For high-risk groups such as adults over 65 and people who are immunocompromised, the CDC recommends an additional booster six months later.
The U.S. appears to be alone in adopting its universal approach. Other countries, particularly in Europe, recommend a more tailored strategy. For example, Sweden and Germany now only recommend that high-risk groups get boosted. And the World Health Organization has adopted a similar approach, stratifying groups and adjusting advice based on comorbidities and age.
Some researchers suggest that additional yearly vaccines may not be necessary for most people given that Covid-19 cases, hospitalizations, and deaths are overall on a downward trend, and infections are much less severe than a few years ago. But others, like Hotez, agree with the CDC guidance, pointing out that additional vaccines help boost waning immunity and protect against chronic conditions such as long Covid and heart complications. “One of the best ways to protect your heart health is to keep up with your boosters,” Hotez said.
Despite the guidance, only about 20 percent of American adults have gotten the latest vaccine to date. This concerns experts like Jessica Malaty Rivera, an infectious disease epidemiologist and senior science communication adviser at the deBeaumont Foundation, which focuses on public health, but she said it doesn’t surprise her: “Covid vaccine fatigue is very real.”
Other concerns, such as what guidance will look like with the new Trump administration, are also beginning to bubble up.
The argument against yearly Covid-19 vaccines, according to some experts, is not that they are damaging, but rather that they may, at this point, be unnecessary for healthy individuals. Most Americans are not getting the yearly vaccination, yet hospitalizations and deaths are still declining, said Paul Offit, a pediatrician specializing in infectious diseases at the University of Pennsylvania School of Medicine. Instead, the boosters appear to most benefit at-risk groups: elderly people, individuals who are immunocompromised, patients who have chronic medical conditions, and people who are pregnant.
“Those are the four big groups who really do benefit from a yearly vaccine,” he said. “Because what they all share, frankly, is they don’t make great immune responses, so they need that sort of repeat dosing.”
“One of the best ways to protect your heart health is to keep up with your boosters.”
Offit’s hunch is that the current U.S. guidance is a way to convince those vulnerable groups to get vaccinated. “The public health community has decided that the best way to get those people who are in high-risk groups vaccinated is to recommend it for everybody,” he said. “I think that they should explain that, if that’s their thinking.”
(In a response to a request for comment, an email sent to Undark by CDC spokesperson Jasmine Reed noted that in developing recommendations, the agency considers “balance of benefits and harms, type or quality of evidence, values and preferences of the people affected, and health economic data analyses.”)
Ultimately, though, the extra vaccinations provide a tinge of extra protection, even if it isn’t necessary, Offit pointed out. “For healthy young people, I think it’s kind of low risk, low reward,” he said, though he acknowledged such people might need boosters in the future if immunity from both natural infection and previous vaccinations begin to fade and they start experiencing more severe disease.
Other experts stand by the CDC guidelines, mainly because they recognize that immunity brought on by Covid-19 vaccination, infection, or both dwindles within the year, especially with evolving variants of the virus. The recommendations are “based on the fact that the durability of protection using this mRNA technology is not as robust as we’d like it to be,” Hotez said.
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Additional yearly vaccinations can also influence the development of long-term consequences beyond just getting infected with Covid-19, Rivera emphasized. “Covid is a virus that affects your cardiovascular health and your neurological health and your overall physical health; it can debilitate people and disable people,” she said. “If you can reduce your risk of having severe outcomes and long-term health complications and deaths, it just seems like a much better way to do that.”
One study published in Nature Communications in 2024 looked at health records from 45.7 million adults in England and found that heart events such as stroke decreased after each vaccine dose. Other studies suggest that receiving a Covid-19 booster vaccine also reduces the risk of developing long Covid. “It’s really more about keeping you out of the hospital, protecting your heart health, and reducing your likelihood of long Covid,” said Hotez.
Kathryn Edwards, a pediatrician who specializes in infectious diseases and vaccines at Vanderbilt University, also agrees with the current CDC Covid-19 booster guidance. Still, she emphasized that higher risk groups in particular “should preferentially get the booster.”
What does the future of Covid boosters look like? Although people in the United States are getting the 2024-2025 Covid vaccine, the 20 percent of vaccinated adults and 11 percent of vaccinated children pales in comparison to the 70 percent of people who got the first round of vaccines. And a survey conducted in October by the Pew Research Center shows that 60 percent of Americans say they will probably not get the latest vaccine. Much of that, experts say, is due to fatigue, concerns about potential side effects, and the fact that people don’t think about harm reduction as a spectrum. “People just want to hear that there’s either no chance of getting it or 100 percent chance,” Rivera said. “And that’s just not how this data work.”
“For healthy young people, I think it’s kind of low risk, low reward.”
Meanwhile, comparing recommendation outcomes across countries can be tricky given the differences in health care, co-morbidities, and ethnicities, she added: “It’s not a one-to-one comparison.”
Despite the nuanced debates on booster guidance, there are a few things that U.S. experts agree on. First, every expert that Undark talked to agreed that boosters provide much needed protection to at-risk populations. Some also emphasized the need for improved messaging from agencies like the CDC on their decisions and ongoing epidemiological studies to continue improving understanding of how the different boosters match up against the current and emerging variants.
For example, Offit would like to see collaborations between the CDC, which generates the epidemiological studies, and academic immunologists to further understand how long immunity really lasts so then vaccinations can be recommended accordingly.
Every expert that Undark talked to agreed that boosters provide much needed protection to at-risk populations.
Many experts are also worried about what guidance and vaccine availability will look like under the new Trump administration, especially given the influence of vaccine skeptic Robert F. Kennedy, Jr., who has been tapped to head the Department of Health and Human Services. Recently, Kennedy’s lawyer petitioned the U.S. government to revoke approval of the polio vaccine, signaling potential changes to come. “I think everybody’s holding their breath and waiting to see what the fallout is going to be,” said Offit.
Hotez’s next Covid-19 vaccination is due in February. But, he said in December, “I probably would get it in early January, just because of the uncertainty whether it’s going to be available or not.”