What Is Abrysvo Used For Rsv Vaccine Explained?

Abrysvo is a vaccine approved by the FDA to protect against respiratory syncytial virus, or RSV. It is used in two distinct groups: adults aged 60 and older, and pregnant people between 32 and 36 weeks of gestation, who pass protection to their newborns. It is not a treatment for RSV. It is given before exposure to lower the risk of serious lung infection.

What Is Abrysvo Used For? RSV Vaccine Explained

Abrysvo is a recombinant protein vaccine. That means it contains lab-made pieces of a protein found on the surface of RSV — not live virus. Your immune system sees those protein pieces and builds a defense against them.

The protein in question is called the F protein. RSV uses it to fuse with your cells and start an infection. The vaccine presents a stabilized form of this protein so the immune system can recognize it before you ever encounter the real virus.

Abrysvo is approved for two uses:

• Preventing lower respiratory tract disease caused by RSV in adults 60 and older
• Protecting infants from RSV through vaccination of the pregnant parent during the third trimester

These are separate populations with separate dosing schedules. The vaccine is not approved for children, and it is not used to treat an active RSV infection.

How Does the Maternal RSV Vaccine Protect Newborns?

Infants cannot receive an RSV vaccine directly at birth. Their immune systems are too immature to mount a strong response. So Abrysvo takes a different route: it vaccinates the pregnant parent, who then passes protective antibodies across the placenta to the fetus.

This is called passive immunity. The parent’s immune system makes antibodies after vaccination. Those antibodies travel through the placenta into the baby’s bloodstream during the final weeks of pregnancy. After birth, the baby has some level of protection that lasts for roughly the first six months of life.

Timing matters. The FDA approved Abrysvo for use between 32 and 36 weeks of gestation. This window allows enough time for antibody transfer before delivery while reducing the risk of preterm birth that was observed when the vaccine was given earlier in pregnancy during clinical trials.

The antibodies fade over time. By around six months, the protection has largely waned. This is one reason a separate monoclonal antibody product — nirsevimab — exists as an alternative for infants. It provides antibodies directly rather than relying on maternal transfer.

Who Should Get Abrysvo and Who Should Not?

The CDC recommends a single dose of RSV vaccine for all adults aged 75 and older. For adults 60 to 74, the recommendation is based on shared clinical decision-making — meaning you and your doctor weigh your personal risk.

Risk factors that may tip the scale toward vaccination include:

• Chronic heart or lung disease
• Weakened immune function
• Diabetes with complications
• Severe obesity
• Living in a nursing home or long-term care facility
• Advanced age within the 60-to-74 range

For pregnant people, the recommendation is a single dose between 32 and 36 weeks of gestation, given from September through January — the months when RSV circulates most in the United States. This timing aligns with the peak RSV season and allows antibody transfer before birth.

Abrysvo is not recommended for anyone with a severe allergic reaction to any component of the vaccine. If you have had a serious allergic reaction to a previous vaccine, tell your healthcare provider before receiving Abrysvo.

How Effective Is Abrysvo Against RSV?

Clinical trials showed that Abrysvo reduces the risk of RSV-related lower respiratory tract disease in older adults. The vaccine’s effectiveness is not 100%, and protection does appear to decline over time — which is why the current guidance focuses on a single dose rather than annual revaccination for most people.

In the maternal trial, vaccination during the third trimester reduced the risk of severe RSV illness in infants during their first six months. The protection was strongest in the first three months after birth and decreased after that.

It is important to understand what these trials measured. They looked at medically attended lower respiratory tract illness — meaning the baby or adult needed to see a doctor or go to the hospital. They did not measure whether the vaccine prevents all RSV infections, including mild ones. No RSV vaccine currently on the market prevents every infection.

Some research suggests that vaccine effectiveness may be somewhat lower in adults with weakened immune systems or those with multiple chronic conditions. The evidence here is still developing.

What Are the Side Effects of Abrysvo?

The most commonly reported side effects in clinical trials were injection site pain, fatigue, headache, and muscle pain. These are typical of most vaccines and usually resolve within a few days.

In the maternal trial, a small imbalance in preterm births was observed when the vaccine was given before 32 weeks. This is why the approved window starts at 32 weeks. Within the approved 32-to-36-week window, the rate of preterm birth was similar between vaccinated and unvaccinated groups.

Serious adverse events were rare in trials. As with any vaccine, there is a small risk of a severe allergic reaction called anaphylaxis. Vaccination providers are equipped to manage this. If you have a history of severe allergies, discuss it with your provider beforehand.

There is no live virus in Abrysvo. You cannot get RSV from the vaccine.

How Does Abrysvo Compare to Other RSV Prevention Options?

There are now three main tools for RSV prevention in the populations most at risk:

• Abrysvo — a vaccine for adults 60 and older, and for pregnant people at 32 to 36 weeks to protect infants
• Arexvy — a vaccine approved for adults 60 and older, not for use in pregnancy
• Nirsevimab (Beyfortus) — a monoclonal antibody given directly to infants, providing immediate but temporary protection

For older adults, both Abrysvo and Arexvy are options. They use similar technology but differ in their exact composition and adjuvant. Some research suggests Arexvy may produce a somewhat stronger immune response in older adults, but direct comparisons are limited and the clinical significance of this difference is not fully established.

For pregnant people, Abrysvo is the only RSV vaccine approved for use during pregnancy. Nirsevimab is an alternative for protecting the infant after birth, given as an injection to the baby rather than the parent.

The choice between maternal vaccination and infant monoclonal antibody is a conversation to have with your healthcare provider. Both approaches reduce the risk of severe RSV in infants, but they work differently and have different logistical considerations.

When Should You Get the RSV Vaccine?

For adults 60 and older, the vaccine can be given at any time of year, though many providers recommend getting it before RSV season begins — typically in the fall. RSV season in the United States generally runs from October through March, though the exact timing varies by region and year.

Abrysvo can be given at the same time as other adult vaccines, including flu and COVID-19 vaccines. If you receive multiple vaccines at once, they may be given in different arms or at different injection sites.

For pregnant people, the timing is more specific. The vaccine should be given between 32 and 36 weeks of gestation, ideally before the RSV season starts or during it. If you are pregnant and entering your third trimester during RSV season, talk to your provider about whether Abrysvo is right for you.

If you already had an RSV vaccine last season, current guidance does not recommend an annual dose for most people. The exception may be adults 75 and older, for whom a single dose is recommended regardless of prior vaccination status. This is an area where recommendations continue to evolve.