Three RSV vaccines are currently approved in the United States: Arexvy (made by GSK), Abrysvo (made by Pfizer), and mResvia (made by Moderna). These cover older adults, and one of them, Abrysvo, is also approved for use during pregnancy to protect newborns. For infants who don’t get protection through maternal vaccination, a separate product called nirsevimab provides ready-made antibodies instead of triggering the body to build its own.
Who the RSV Vaccines Are For
The CDC recommends an RSV vaccine for all adults 75 and older. Adults between 50 and 74 are also recommended to get one if they have risk factors for severe RSV illness, including chronic heart or lung disease, a weakened immune system, other underlying medical conditions, or living in a nursing home. All three vaccines (Arexvy, Abrysvo, and mResvia) are available for adults 50 and older.
For younger adults ages 18 to 49, two of the three vaccines, Abrysvo and mResvia, are approved for those at increased risk of serious RSV-related lung infection. This is a newer expansion of eligibility, so it’s worth asking your pharmacist or doctor whether you qualify.
How the Vaccines Work
Arexvy and Abrysvo are protein subunit vaccines. They contain a lab-made version of a protein found on the surface of the RSV virus. Your immune system recognizes that protein as foreign, builds antibodies against it, and remembers how to fight the real virus if you’re exposed later. This is the same basic approach used in many well-established vaccines.
mResvia takes a different route. It’s an mRNA vaccine, similar in concept to the COVID-19 mRNA shots. Instead of delivering the protein directly, it delivers genetic instructions that tell your cells to temporarily produce the RSV surface protein themselves. Your immune system then responds to that protein the same way. The mRNA breaks down naturally and never integrates into your DNA.
How Well They Work in Older Adults
In pooled clinical trial data from both the GSK and Pfizer vaccines, adults 75 and older who were vaccinated had about 69% lower rates of RSV-related lower respiratory tract disease compared to those who received a placebo. For adults 60 to 74 with risk factors for severe illness, protection was even slightly better at around 73%. Vaccine efficacy against hospitalization for RSV respiratory illness was roughly 76% across age groups studied, though the confidence intervals were wide because hospitalizations were relatively uncommon events in the trials.
The Pregnancy Vaccine for Newborns
Abrysvo is the only RSV vaccine approved for use during pregnancy, and it works by a simple principle: a pregnant person builds antibodies after vaccination, and those antibodies cross the placenta to the baby before birth. The result is that the newborn arrives with built-in protection during the months when they’re most vulnerable.
The CDC recommends a single dose of Abrysvo between 32 and 36 weeks of pregnancy, given sometime between September and January (the typical RSV season window). Timing matters. If vaccination happens after 36 weeks and 6 days, there likely isn’t enough time for antibodies to develop and transfer to the baby.
The clinical trial results were striking. Within the first three months after birth, the maternal vaccine reduced the risk of an infant being hospitalized for RSV by 68% and the risk of needing any healthcare visit for RSV by 57%. It cut the risk of the most severe outcomes, including dangerously low oxygen levels, mechanical ventilation, or ICU admission, by 82%. At six months after birth, protection naturally waned somewhat but remained meaningful: 57% reduction in hospitalization and 69% reduction in severe outcomes.
Antibody Protection for Infants
Nirsevimab (brand name Beyfortus) isn’t technically a vaccine. It’s a lab-made antibody injection given directly to infants, providing immediate protection rather than training the immune system to make its own defenses. Think of it as a shortcut: the baby gets pre-built tools to fight RSV right away.
It’s recommended for infants younger than 8 months who are entering their first RSV season, specifically when the mother either didn’t receive the Abrysvo vaccine during pregnancy, her vaccination status is unknown, or the baby was born within 14 days of the mother’s vaccination (not enough time for antibodies to transfer). Children between 8 and 19 months who are at increased risk for severe RSV can also receive it before their second RSV season, at a higher dose.
Nirsevimab and maternal vaccination serve the same purpose, protecting the infant, so most babies need one or the other, not both.
Side Effects and Safety Concerns
Common side effects of the RSV vaccines for adults are typical of most vaccines: soreness at the injection site, fatigue, headache, and muscle pain. These generally resolve within a day or two.
The more notable safety concern involves Guillain-Barré syndrome, a rare neurological condition where the immune system attacks nerve cells, causing muscle weakness and sometimes temporary paralysis. The FDA now requires a GBS warning on the prescribing information for both Abrysvo and Arexvy. Post-market data in adults 65 and older suggest an estimated 9 excess cases of GBS per million doses of Abrysvo and 7 excess cases per million doses of Arexvy within 42 days of vaccination. In the original clinical trials, GBS occurred in a very small number of vaccinated participants: two cases among roughly 22,000 Abrysvo recipients and one case among roughly 16,000 Arexvy recipients. The risk is real but very low, and for most people in the recommended age groups, the protection against severe RSV disease outweighs it.
Cost and Insurance Coverage
If you have Medicare Part D or a Medicare Advantage plan with drug coverage, the RSV vaccine is covered at no cost to you. There’s no copayment or deductible. Part D covers all vaccines recommended by the CDC’s Advisory Committee on Immunization Practices, and RSV is on that list. For those with private insurance, coverage varies by plan, but most insurers cover CDC-recommended vaccines. Without insurance, the out-of-pocket cost for RSV vaccines can run over $200, so it’s worth confirming your coverage before scheduling.