Yes, RSV vaccines are very new. The first RSV vaccine for any age group received FDA approval in May 2023, making these among the newest vaccines available. Scientists had been trying to develop an RSV vaccine since the 1960s, but a tragic early failure set the effort back by decades. After more than 50 years of research, three RSV vaccines are now approved in the United States, with the most recent arriving in June 2024.
Why It Took Over 50 Years
RSV, or respiratory syncytial virus, infects nearly everyone at some point in life and causes thousands of hospitalizations each year, particularly among infants and older adults. Researchers first attempted a vaccine in 1967 using a standard approach: they inactivated (killed) the virus and injected it, hoping to train the immune system. It didn’t work. Not only did the vaccine fail to protect children, it made subsequent natural RSV infections far worse. Vaccinated children who later caught RSV in their communities developed severe lung inflammation, a reaction researchers call enhanced respiratory disease.
Later studies revealed why. The inactivated vaccine produced antibodies that couldn’t actually neutralize the virus. When the real virus showed up, the immune system launched an exaggerated, misdirected inflammatory response in the lungs instead of clearing the infection. This disaster created deep caution among researchers and regulators, effectively pausing RSV vaccine development for decades while scientists worked to understand the virus’s biology well enough to avoid repeating the problem.
The breakthrough came from structural biology. Researchers eventually mapped the shape of the RSV surface protein (called the F protein) in its “prefusion” form, the shape it takes before it enters a cell. Targeting this specific form of the protein turned out to produce strong, neutralizing antibodies without the dangerous inflammatory response that doomed the 1967 vaccine.
The Three Approved Vaccines
GSK’s Arexvy became the first-ever approved RSV vaccine in May 2023, authorized for adults 60 and older. Pfizer’s Abrysvo followed shortly after, also in 2023, with approval for both older adults and pregnant women. Then in June 2024, Moderna’s mResvia became the third option, using mRNA technology (similar to some COVID-19 vaccines) to instruct cells to build that same prefusion F protein and trigger an immune response. All three vaccines target the same viral protein but use different delivery methods to get there.
Each vaccine is given as a single dose. Arexvy and Abrysvo are protein-based vaccines, meaning they deliver a lab-made version of the viral protein directly. mResvia delivers genetic instructions that let your own cells produce the protein temporarily. The end result is the same: your immune system learns to recognize and fight RSV before you encounter it naturally.
Who Is Eligible
The CDC recommends the RSV vaccine for all adults 75 and older, plus adults ages 50 to 74 who have conditions that raise their risk of severe RSV illness. Those conditions include chronic heart disease, chronic lung conditions like COPD or asthma, diabetes with organ damage or insulin dependence, severe obesity (BMI of 40 or higher), weakened immune systems, chronic liver or kidney disease, and neurological conditions that affect breathing or swallowing. Living in a nursing home also qualifies you.
You don’t need medical records to prove eligibility. The CDC’s guidance states that simply telling your vaccinator you have a qualifying condition is sufficient, and providers should not deny vaccination for lack of documentation.
Protection for Newborns
One of the more notable developments is the option to protect newborns through maternal vaccination. The CDC recommends that pregnant women receive one dose of Pfizer’s Abrysvo between 32 and 36 weeks of pregnancy, during September through January. The vaccine prompts the mother’s immune system to produce antibodies that cross the placenta and protect the baby after birth. This protection wanes over time, but because the vaccine is timed to the RSV season (which peaks in fall and winter), it covers the infant through their first vulnerable months.
This maternal approach exists alongside another option for infants: a preventive antibody injection (not technically a vaccine) called nirsevimab, which gives babies ready-made antibodies directly. Parents and providers can choose one strategy or the other based on timing and circumstances.
Side Effects and Safety Signals
Common side effects mirror those of most vaccines: injection-site pain, fatigue, headache, and muscle aches. These are typically mild and resolve within a few days.
One rare but serious concern has surfaced since the vaccines became available. Postmarketing surveillance of Medicare recipients 65 and older found a possible link between RSV vaccination and Guillain-Barré syndrome (GBS), a nerve condition that causes weakness and sometimes temporary paralysis. The FDA estimates roughly 7 to 9 extra cases of GBS per million doses administered, depending on the vaccine. The risk appears concentrated in the 42 days following vaccination. The FDA has required updated warning labels on both Abrysvo and Arexvy, though it notes the evidence suggests an increased risk without definitively proving the vaccines cause GBS. During clinical trials, a small number of GBS cases appeared within days of vaccination, which prompted the closer monitoring that eventually led to the label change.
What “New” Means in Practice
Because these vaccines have only been in use since mid-2023, long-term data is still limited compared to vaccines that have been around for decades. Scientists know the vaccines work well to reduce severe lower respiratory disease in the first season or two after vaccination, but questions remain about how long protection lasts and whether booster doses will eventually be needed. The current recommendation is for a single dose rather than annual revaccination.
For context, RSV hospitalizes an estimated 60,000 to 120,000 older adults in the U.S. each year and is a leading cause of infant hospitalization. The fact that effective vaccines now exist at all represents a major shift. For most of modern medicine, RSV was considered one of the most important infectious diseases without a vaccine. That changed in 2023, making the RSV vaccine one of the newest additions to the immunization landscape.