You're probably used to the annual flu shot dance. Every October, the signs go up at CVS, you roll up your sleeve, and you're good for another twelve months. So, when the FDA first greenlit those shiny new Respiratory Syncytial Virus (RSV) vaccines in 2023, most people naturally assumed we were looking at another yearly ritual. It makes sense, right? But here's the thing: how often to get RSV vaccination isn't actually following the flu or COVID playbook.
Honestly, the current guidance is a bit of a curveball.
As of right now, the CDC hasn't called for an annual booster. Not yet. If you grabbed your shot last year when they first hit the market, the official word from the big desks at the Advisory Committee on Immunization Practices (ACIP) is basically "hold steady." They aren't seeing the same rapid immunity drop-off we see with other respiratory bugs. It’s weirdly refreshing.
The "One and Done" For Now Reality
The biggest point of confusion involves whether this is a seasonal requirement. We know RSV peaks in the winter. It’s a nasty lower respiratory tract disease that sends between 60,000 and 160,000 older adults to the hospital every single year. So the urgency is real. But if you're looking for a hard number on how often to get RSV vaccination, the answer is currently: once.
That might change. Science is messy and iterative.
When GSK (Arexvy) and Pfizer (Abrysvo) ran their initial clinical trials, they didn't just look at one season. They followed people through a second year. What they found was pretty surprising. The protection against severe lung infections stayed remarkably high even through that second winter. Because the efficacy didn't plummet, the medical community didn't see a reason to poke people again so soon.
It’s about durability.
The immune system seems to "remember" the RSV protein used in these vaccines—specifically the prefusion F protein—better than it remembers the ever-mutating surface proteins of the flu. Flu viruses are master shapeshifters. RSV is more of a slow-moving target. That stability is exactly why you aren't currently being told to go back for a second round this year.
Who Actually Needs to Worry About Timing?
The rules aren't identical for everyone. We have to look at the three main groups: seniors, pregnant people, and infants.
For the 60-plus crowd, the recommendation changed slightly in mid-2024. The CDC now "strongly recommends" the vaccine for everyone aged 75 and older. If you’re between 60 and 74, they suggest it only if you have underlying stuff like heart disease or COPD. If you got it at age 67, and you're now 68? You're still covered. No second dose.
Pregnant people have a very narrow window. This is about protecting the baby, not just the parent.
If you're pregnant, the timing is hyper-specific: between 32 and 36 weeks of gestation, and specifically during RSV season (usually September through January in most of the US). This sends antibodies through the placenta. It’s a brilliant bit of biology. But if you have a second pregnancy two years later? You'll likely need another shot then. That’s the exception to the "one and done" rule because you’re dosing for a new human.
Why We Don't Have a Forever Answer Yet
You might feel like the goalposts keep moving. They kinda do.
Dr. Nirav Shah, the Principal Deputy Director of the CDC, has been pretty transparent about the fact that they are watching the data in real-time. They are looking for "breakthrough" cases. If people who were vaccinated in 2023 start showing up in ERs in large numbers in 2026, the guidance on how often to get RSV vaccination will shift to a biennial or triennial schedule.
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We also have to talk about the new kid on the block: Moderna’s mRESVIA.
This is an mRNA vaccine, similar to the COVID shots but specifically for RSV. It was approved in early 2024 for seniors. Does mRNA protection last as long as the protein-based versions from GSK and Pfizer? We don't fully know. The early data says it’s solid for at least a season, but the long-term durability is the million-dollar question. If you chose the Moderna route, you're still in the "one dose only" camp for now, but that’s the group experts are watching most closely for signs of waning immunity.
The Nuance of Seasonality
Location matters. If you're in Florida, RSV season starts earlier and lasts longer than it does in, say, Montana.
- Standard Season: October to April.
- Best time to vax: Late summer or early fall (August/September).
- The "Late" Factor: If you missed the fall window, it's usually still worth getting through mid-winter.
If you already had RSV recently, you might wonder if you can skip the shot. Natural immunity is a thing, sure. But natural immunity against RSV is notoriously fleeting. You can catch RSV over and over again throughout your life. The vaccine is designed to produce a much more robust and "sticky" immune response than a natural infection usually does.
Side Effects vs. Benefits
Nobody likes a sore arm. Some people reported feeling a bit wiped out or having a low-grade fever after the RSV shot. There was also a very small, "statistical signal" regarding Guillain-Barré Syndrome (GBS) in the initial rollout. We're talking maybe 1.5 cases per million doses.
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To put that in perspective, the risk of ending up on a ventilator from RSV if you're 80 years old is astronomically higher than the risk of GBS. Doctors are weighing these risks every time they update the frequency guidelines. Right now, the benefit of that single dose is so high that the risk-reward profile is heavily skewed toward vaccination—but only once.
Actionable Next Steps for Staying Protected
Don't just wait for a reminder card in the mail. Health systems are still catching up to the RSV rollout.
Check your records. If you haven't received an RSV vaccine since their debut in 2023 and you are over 75, or over 60 with a chronic condition, get it now. One dose is all it takes to significantly lower your risk of viral pneumonia.
Consult your pharmacist about "co-administration." You can actually get your RSV shot at the same time as your flu shot. It’s convenient. Some studies suggest a slightly higher rate of minor side effects (like fatigue) when you double up, but the actual immune response stays strong for both.
If you are currently pregnant and entering your third trimester, talk to your OB-GYN immediately about the 32-36 week window. Timing is everything here. If the parent gets vaccinated, the baby usually doesn't need the monoclonal antibody (nirsevimab) later. It saves the infant a needle.
Monitor the CDC's Morbidity and Mortality Weekly Report (MMWR) or just check back with your doctor every September. While the current answer to how often to get RSV vaccination is "once for the foreseeable future," the fall of 2025 or 2026 could bring new data that suggests a two-year booster cycle.
Stay informed, but don't over-vaccinate. More isn't always better; right now, the single dose you've already had (or are about to get) is doing the heavy lifting.