The RSV vaccine is a one-time shot, not an annual vaccine. Unlike the flu vaccine, which you need every fall, the CDC recommends just a single dose of the RSV vaccine for eligible adults, with no booster or repeat dose at this time. If you’ve already received one dose, you’re considered fully vaccinated.
Who Should Get the Single Dose
The CDC recommends an RSV vaccine for two groups of adults: everyone 75 and older, and adults between 50 and 74 who are at increased risk of severe RSV illness. Risk factors in that younger age group include chronic lung or heart disease, a weakened immune system, and living in a nursing home or long-term care facility.
If you’re in one of these groups and haven’t been vaccinated yet, one dose is all you need. The CDC is explicit that people who have already received one dose “have completed their vaccination and should not receive another dose at this time.”
How Long Protection Lasts
Clinical trial data shows the vaccine holds up reasonably well into a second RSV season, though protection does fade. Pfizer’s vaccine maintained 77.8% efficacy against severe RSV lung disease through two full seasons. Against milder illness, efficacy dropped from about 65% after the first season to around 56% after the second.
A large phase 3 trial of GSK’s vaccine, published in The Lancet Respiratory Medicine, tracked efficacy across three RSV seasons and confirmed a gradual decline over time. That waning is part of why researchers have been studying whether a booster might help.
Why There’s No Booster Yet
The short answer: a booster shot given one year after the initial dose didn’t meaningfully improve protection. In the GSK trial, about 5,000 people received a second dose before their second RSV season, while a similar group received a placebo instead. By the third season, efficacy in the booster group was 68.4%, which was roughly in the same range as the single-dose group. A second shot, in other words, didn’t offer a clear advantage over the original one.
This doesn’t mean boosters are permanently off the table, but for now, the data doesn’t support them. The CDC continues to evaluate whether repeat dosing will eventually be recommended, and guidelines could change as more long-term data becomes available.
RSV Vaccination During Pregnancy
Pregnant women have a different set of guidelines. A single dose of the maternal RSV vaccine can be given during weeks 32 through 36 of pregnancy, ideally between September and January, to pass protective antibodies to the baby before birth. This is offered as an alternative to giving the infant a separate RSV antibody injection after delivery.
If you received the maternal RSV vaccine during a previous pregnancy, the CDC does not currently recommend getting another dose in subsequent pregnancies. Researchers are still evaluating whether revaccination in later pregnancies provides enough additional benefit to justify a second dose, but for now, one pregnancy dose is the guidance.
Protection for Infants and Young Children
Babies and toddlers don’t receive the RSV vaccine itself. Instead, infants are protected either through their mother’s vaccination during pregnancy or through an antibody injection called nirsevimab, given directly to the baby. Most infants need just one dose during their first RSV season.
A small subset of higher-risk children between 8 and 19 months old may receive a second dose heading into their second RSV season. This applies to children with chronic lung disease of prematurity, severe immune compromise, cystic fibrosis with significant lung involvement, or American Indian and Alaska Native children. For these kids, the optimal timing is shortly before RSV season begins, typically in October or November. The second-season dose is larger, given as two separate injections.
What Happens if You Get an Extra Dose
Reports of accidental extra doses have been increasing as the vaccine has become more widely available. An analysis of the Vaccine Adverse Events Reporting System found that extra doses accounted for 36.2% of reported vaccination errors in 2025, up from just 2.4% in 2023. While the data doesn’t point to serious harm from an accidental second dose, the rising error rate underscores how easily it can happen, especially since RSV vaccination is new and doesn’t yet have the established annual rhythm of the flu shot. Keeping a record of your vaccination, whether through your pharmacy, doctor’s office, or state immunization registry, helps avoid this.
How RSV Vaccination Compares to Other Vaccines
- Flu vaccine: New dose every year, because flu strains change seasonally.
- COVID vaccine: Updated doses recommended periodically as variants evolve.
- RSV vaccine: Single dose with no current booster recommendation. RSV doesn’t mutate as rapidly as flu or COVID, which is one reason a single dose provides longer-lasting protection.
- Shingles vaccine: Two doses given 2 to 6 months apart, then no further doses needed. The closest parallel to RSV in terms of being a “one and done” adult vaccine.
The simplest way to think about it: if you’re eligible and you’ve had one RSV shot, you’re set for now. Keep an eye on updated CDC guidance each fall, since recommendations could shift as researchers learn more about how long immunity holds up beyond three seasons.