Some older adults may not be getting as much long-term protection from RSV vaccination as they think—and that raises a big question: should certain people be getting a booster shot to stay protected longer?
What the study set out to answer
Current guidelines say that older adults only need a single RSV shot, but there has not been much long-term data showing how long that protection actually lasts in real-world conditions.
In response, researchers looked at how well RSV vaccines worked over time in a large group of U.S. veterans ages 60 and older, focusing on both overall effectiveness and how protection changed month by month.
Their goal was not only to measure short-term benefits, but also to see whether high-risk groups—especially people with weakened immune systems—might need a different vaccination strategy.
How protection changed over 18 months
Right after vaccination, protection against getting RSV infection was strong, with effectiveness estimated at just over 80% in the first month after the shot (starting 14 days after vaccination).
However, this protection gradually declined, dropping to around 60% by 18 months, suggesting that immunity against infection does not stay at peak levels indefinitely.
The decline was even more concerning in people who were immunocompromised, where effectiveness fell from about 75% initially to roughly 40% over the same period.
Impact on serious illness and hospitalization
Even as protection against infection waned, the vaccines continued to provide substantial defense against severe outcomes like hospitalization and intensive care treatment.
In the first month, effectiveness against RSV-related hospitalization was close to 90%, and although it decreased over time, it still remained above 50% at 18 months, indicating a meaningful ongoing benefit.
Protection against ICU admission started above 90% and, while it also dropped, stayed around 70% at 18 months, which suggests that vaccinated older adults were still significantly less likely to end up critically ill.
Who was included in the research
The study used electronic health records from the Veterans Health Administration and compared 288,111 vaccinated veterans with an equal number of similar but unvaccinated veterans.
Most participants were men (about 94.5%), with a median age of 76, and the majority were white, which is important because it may limit how well the findings apply to more diverse populations.
Many had other health problems: nearly half had cardiovascular disease, about 41% had diabetes, around 31% had chronic lung disease, and about 6.5% were immunocompromised, making this a generally high-risk group.
One dose, or is a booster needed?
At present, RSV vaccines are approved for older adults, and U.S. health authorities recommend a single dose for all adults 75 and older, as well as for adults ages 50–74 who have a higher risk of severe disease.
The new data support the idea that vaccination clearly helps people 60 and older, especially when it comes to preventing serious RSV-related complications that lead to hospital or ICU care.
However, the noticeable drop in protection over time—particularly in immunocompromised individuals—has led the study authors to suggest that the potential benefits and risks of a second dose (a “booster”) in certain groups should be carefully studied.
Differences between age groups and vaccines
Interestingly, not all age groups experienced the same pattern of waning; adults 65 and older generally showed declining effectiveness over time, while those ages 60–64 seemed to maintain more stable protection across the follow-up period.
The study also found that one of the RSV prefusion F protein-based vaccines (Arexvy, which is adjuvanted) appeared to perform better over 18 months than the bivalent prefusion F vaccine (Abrysvo), with estimated effectiveness of about 65% versus 56%, respectively.
This kind of difference could influence how clinicians and policymakers think about which product to prefer for certain patients—but it may also fuel debate about whether all vaccines in the same category should be treated as interchangeable.
Real-world coverage: a gap between guidance and reality
Despite clear recommendations and the demonstrated benefits, uptake of RSV vaccination among older adults has been relatively low through the end of the 2024–2025 respiratory season.
Fewer than half of adults aged 75 and older (about 48%) reported receiving an RSV vaccine, and only about 38% of high-risk adults ages 60–74 were vaccinated, leaving many people who could benefit still unprotected.
This disconnect between strong clinical evidence and modest real-world uptake is one of the most striking—and arguably most controversial—findings: are vaccines truly underused, or are people still unconvinced they are necessary?
Study strengths, limitations, and what they mean
The researchers designed the analysis to mimic a randomized clinical trial as closely as possible using real-world data, which strengthens confidence that the differences between vaccinated and unvaccinated groups are meaningful.
At the same time, there are important limitations: only about 10% of eligible veterans received an RSV vaccine, records might miss infections or outcomes that occurred outside the VA system, and the largely white, male veteran population may not reflect how RSV vaccines perform in women, minority groups, or non-veteran communities.
These caveats open the door for differing interpretations—some may see the results as strong support for boosters in high-risk groups, while others may argue that more diverse, prospective trials are needed before changing national recommendations.
What experts are saying now
In an accompanying editorial, outside experts emphasized that real-world evidence like this is crucial for shaping vaccination policy and that these findings support continued RSV vaccination efforts for adults 60 and older, especially those at higher risk.
They acknowledged that boosters might eventually be needed but argued that, for now, the top priority should be protecting the most vulnerable by increasing first-dose coverage among adults 75+ and those 60+ with underlying health conditions.
This position itself could be seen as debatable: should health systems push harder for broader initial coverage before even talking about boosters, or start planning booster strategies now for those whose protection is fading fastest?
The part most people miss
One detail that often gets overlooked is that vaccine effectiveness at 6–12 months looked similar to 12–18 months, suggesting that the biggest drop in protection may occur relatively early, then level off.
For adults ages 60–64, effectiveness stayed stable over time, hinting that a “one size fits all” schedule may not be ideal and that age-tailored or risk-based booster strategies could make more sense in the future.
And this is the part most people miss: differences between age brackets, immune status, and vaccine type could eventually lead to more personalized RSV vaccine recommendations rather than a single universal rule.
Questions for you
Given this evidence of waning protection—especially in immunocompromised older adults—do you think health authorities should move faster to study and possibly recommend RSV boosters for high-risk groups, or is it better to wait for more diverse, long-term data first?
Do you feel that focusing on getting more people their first RSV shot is the right priority right now, or should booster planning already be front and center in public health discussions?
Would you personally be comfortable getting an RSV booster if your doctor recommended it based on your age or health conditions, or do you think the current “one-and-done” approach is enough for now?
