Respiratory syncytial virus or RSV is a highly contagious virus that causes mild, cold-like symptoms in most people. The virus is especially common in children, and most young children have been infected with RSV by the time they are two years old. Some people, particularly infants and older adults, are more likely to develop severe RSV disease and need hospitalization.

RSV is seasonal, typically starting in the U.S. during the fall and peaking in the winter.

RSV and Infants

Most infants and young children with RSV have mild, cold-like symptoms. But some infants, especially during their first infection, develop lower respiratory tract disease (LRTD) such as pneumonia (a lung infection) or bronchiolitis (swelling of the small airway passages in the lungs). Premature infants, and those with chronic lung disease of prematurity or significant congenital heart disease, are at highest risk for complications from RSV infection. Pneumonia and bronchiolitis often lead to an emergency department or doctor office visit. RSV is the most common cause of infant hospitalization in the U.S.

Preventing RSV in Infants

There is an FDA-approved vaccine for pregnant individuals at 32 to 36 weeks gestational age to prevent LRTD and severe LRTD caused by RSV in infants from birth through 6 months of age.

Two FDA-approved monoclonal antibodies can help protect infants from RSV LRTD. Monoclonal antibodies are not vaccines. Monoclonal antibodies are laboratory-made proteins that mimic the immune system’s ability to fight off harmful pathogens such as viruses.

CDC recommends all children younger than 8 months receive nirsevimab, a monoclonal antibody, to protect them in their first RSV season. If your child is at increased risk for severe RSV disease, talk to their doctor to determine if additional doses of monoclonal antibodies are recommended for your child (aged 8 to 19 months) as they enter their second RSV season.

The second monoclonal antibody, palivizumab, is limited to children under 24 months of age with certain conditions that place them at high risk for severe RSV disease. It must be given once a month during RSV season.

RSV and Older Adults

In older adults, RSV infection can lead to LRTD, hospitalization, and death. Older adults with certain pre-existing health conditions such as asthma, chronic obstructive pulmonary disease, diabetes, and heart disease are at increased risk for hospitalization, and those with weakened immune system can have severe RSV disease.

Preventing RSV in Older Adults

There are two FDA-approved vaccines to prevent RSV LRTD  in adults ages 60 and older - Abrysvo and Arexvy. Talk to a health care provider to see if an RSV vaccine is right for you.

RSV Tests

Talk to a health care provider if you think you, or your child, have a respiratory illness such as RSV, COVID-19 or the flu. There are home collection tests available for all three illnesses. You can also talk to a health care provider about getting tested.

RSV Treatments

Most people with RSV will have mild, cold-like symptoms and can recover at home. Be sure adults and children with RSV symptoms get enough fluid (water and other fluids). Treat pain and fever as suggested by a health care professional. Most RSV infections go away on their own within two weeks.

RSV can be more dangerous for infants and older adults. If you or your child have trouble breathing or cannot drink or eat enough to stay hydrated (get enough fluid), call 911 or talk to a health care professional right away.

Respiratory syncytial (sin-SISH-uhl) virus, or RSV, is a common respiratory virus that usually causes mild, cold-like symptoms. Most people recover in a week or two, but RSV can be serious. Infants and older adults are more likely to develop severe RSV and need hospitalization. Vaccines are available to protect older adults from severe RSV. Monoclonal antibody products are available to protect infants and young children from severe RSV.

CDC Recommendations

Adults 60 years old and over

• Adults 60 years of age and older may receive a single dose of RSV vaccine using shared clinical decision-making.

Infants and young children

• 1 dose of nirsevimab for all infants younger than 8 months born during or entering their first RSV season.
• 1 dose of nirsevimab for infants and children 8–19 months old who are at increased risk for severe RSV disease and entering their second RSV season.
• Note: A different monoclonal antibody, palivizumab, is limited to children under 24 months of age with certain conditions that place them at high risk for severe RSV disease. It must be given once a month during RSV season. Please see AAP guidelines for palivizumab.

Pregnant people

• 1 dose of maternal RSV vaccine during weeks 32 through 36 of pregnancy, administered immediately before or during RSV season. Abrysvo is the only RSV vaccine recommended during pregnancy.

If you have any questions about RSV or the products above, talk to your healthcare provider.

Nirsevimab (Beyfortus) is an immunization recommended for all infants younger than 8 months of age who are born during—or who are entering—their first Respiratory Syncytial Virus (RSV) season. Except in rare circumstances, most infants younger than 8 months of age do not need nirsevimab if they were born 14 or more days after their mother got RSV vaccine. Nirsevimab is also recommended for some children age 8 through 19 months who are at increased risk for severe RSV disease and entering their second RSV season.

When is RSV season?

In most regions of the United States, RSV season starts in the fall and peaks in the winter, but the timing and severity of RSV season can vary from place to place and year to year. Talk to your child’s health care provider about when is the right time for your child to get nirsevimab based on the RSV season in your community, so that your child is protected against RSV disease.

How can RSV disease be prevented?

RSV disease can be prevented either by giving antibody products to infants and young children, or by giving their mothers RSV vaccine during pregnancy. For most babies, either the maternal RSV vaccine or the preventive antibody is recommended to prevent RSV disease, but not both.

RSV preventive antibody products

There are two RSV antibody products that can help prevent severe RSV disease in infants and young children: Nirsevimab (Beyfortus), and Palivizumab (Synagis).

Nirsevimab is recommended for:

• All infants younger than 8 months of age born during RSV season or entering their first RSV season. Except in rare circumstances, most infants younger than 8 months of age do not need nirsevimab if they were born 14 or more days after their mother got RSV vaccine.
• Some children aged 8 through 19 months who are at increased risk for severe RSV disease and entering their second RSV season.

Palivizumab (Synagis) use is limited to:

• Some children younger than age 24 months of age with certain conditions that place them at increased risk for severe RSV disease. It must be given once a month during RSV season.

RSV vaccine

An RSV vaccine (Abrysvo, Pfizer) is recommended during weeks 32 through 36 of pregnancy to prevent severe RSV disease in infants. This vaccine should typically be given September through January.

Who should get nirsevimab?

• Nirsevimab is recommended for infants younger than 8 months of age who were born during or are entering their first RSV season if
  • The mother did not receive RSV vaccine during pregnancy.
  • The mother’s RSV vaccination status is unknown.
  • The infant was born within 14 days of maternal RSV vaccination.

Most infants whose mothers got the RSV vaccine don’t need to get nirsevimab, too.

• Some infants and young children 8 through 19 months of age who are at increased risk for severe RSV disease should receive nirsevimab shortly before the start of their second RSV season:
  • Children who were born prematurely and have chronic lung disease
  • Children with severe immunocompromise
  • Children with cystic fibrosis who have severe disease
  • American Indian and Alaska Native children

Children who should get nirsevimab but have not yet done so may get nirsevimab at any time during RSV season.

How is nirsevimab administered?

Nirsevimab is administered as a shot into the thigh muscle. Only a single dose (i.e., one shot) of nirsevimab is recommended during an RSV season.

Who should not get nirsevimab?

Children 8 months old and older who are not at increased risk for severe RSV disease  should not receive nirsevimab.

Except in rare circumstances, most infants younger than age 8 months do not need to get nirsevimab if their mothers got the RSV vaccine at least 14 days before delivery.

Infants and children with a history of serious allergic reactions to nirsevimab or any of its components should not get nirsevimab.

Infants and children with bleeding disorders such as hemophilia should get nirsevimab. But, as with all shots given into a muscle, parents should notify their child’s healthcare provider so additional precautions can be taken. 

Infants and children who have a moderate or severe acute illness usually should wait until they recover before getting nirsevimab. Your child’s healthcare provider may decide to postpone giving nirsevimab until a future visit when your child feels better.  Children with minor illnesses, such as a cold, can receive nirsevimab.

How well does nirsevimab work?

Nirsevimab reduces the risk of severe RSV disease by about 80%. One dose of nirsevimab protects infants for at least 5 months, the length of an average RSV season. Because nirsevimab does not activate the immune system, protection is most effective in the weeks right after nirsevimab is given and lessens over time. Nirsevimab does not provide long-term protection to RSV disease, but it does protect infants when they are most at risk of getting very sick from RSV. As children get older, they are less likely to get very sick from RSV.

How does nirsevimab prevent RSV disease?

Nirsevimab contains monoclonal antibodies, which are man-made proteins that protect against RSV. Though it does not activate the immune system the way an infection or vaccine would, a nirsevimab shot provides protection similar to that of a vaccine.

The protection that nirsevimab provides is called “passive immunity” because it does not come from the person’s own immune system. Instead, the protection comes from antibodies produced outside a person’s body.

On the other hand, the protection that vaccines provide is called “active immunity” because the antibodies are made by a person’s own immune system. “Active immunity” requires a person’s immune system to take action to defend itself.

What are the possible side effects of nirsevimab?

Side effects after Nirsevimab were uncommon in clinical trials. The most common side effects after nirsevimab are pain, redness, or swelling where the injection was given, and a rash. No serious allergic reactions occurred in the clinical trials.

As with any immunization, there is a very remote chance that nirsevimab could cause a severe allergic reaction, other serious injury, or death.

If you have any questions about side effects from nirsevimab, talk with your child’s health care provider.

If your child experienced side effects after receiving nirsevimab it can be reported to the FDA or CDC. Your healthcare provider might file the report, or you can do it yourself by phone or through the MedWatch or VAERS websites. them

• Report side effects that happen after getting nirsevimab to the MedWatch website or by calling 1-800-FDA-1088.
• If your child also received any vaccine on the same day as nirsevimab, the side effects also may be reported to VAERS, the Vaccine Adverse Event Reporting System through the VAERS website or by calling 1-800-822-7967.

How do I pay for nirsevimab?

Vaccines for Children (VFC) program
Nirsevimab will be covered by VFC, a federally funded program that provides vaccines at no cost to children who might not otherwise be vaccinated because of inability to pay. Children younger than 19 years of age are eligible for the VFC Program if they belong to one or more of the following groups:

• Medicaid-eligible
• Uninsured
• Underinsured
• American Indian or Alaska Native 

Private health insurance. Many private health insurance plans cover nirsevimab, but there may be a cost to you depending on your plan. Contact your insurer to find out.

What types of RSV vaccines are there?

There are two RSV vaccines licensed by the U.S. Food and Drug Administration for use in adults 60 and older in the United States:

• RSVPreF3 (Arexvy)
• RSVpreF (Abrysvo)

Both vaccines contain a part of the RSV virus. Both vaccines work by causing an immune response that can protect you from respiratory disease if you are infected with RSV in the future.

Who should talk to their healthcare provider about RSV vaccination?

Adults 60 years and older should talk with their health care provider about whether RSV vaccination is right for them. There is no maximum age for getting RSV vaccination. RSV vaccine is given as a single dose.

If you’re 60 or older, your health care provider might recommend RSV vaccination for you, especially if you have a weakened immune system from illness (e.g., leukemia or HIV infection) or from medications (e.g., treatment for cancer or organ transplant), if you have chronic medical conditions such as heart or lung disease, or if you live in a nursing home. If any of those apply to you, you might be at higher risk of severe RSV disease and an RSV vaccine could help prevent serious illness.

Even if you had RSV infection in the past, RSV vaccination can help prevent future respiratory disease from RSV. There is no specific length of time that you need to wait after having RSV infection before you can receive an RSV vaccine, but generally, if you have a moderate or severe illness, you should wait until you recover before receiving an RSV vaccine. If you have a minor illness, such as a cold, you can get an RSV vaccine.

Who should not get RSV vaccination?

You should not get the RSV vaccine Arexvy if you’ve ever had a severe allergic reaction to any component of Arexvy. Information about Arexvy can be found in the manufacturer’s package insert.

You should not get the RSV vaccine Abrysvo if you’ve ever had a severe allergic reaction to any component of Abrysvo. Information about Abrysvo can be found in the manufacturer’s package insert.

How well do these vaccines work?

One dose of RSV vaccine provides protection against RSV disease in adults ages 60 years and older for at least two winter seasons, when RSV normally circulates.

• In adults ages 60 years and older with healthy immune systems, one dose of the RSV vaccine Arexvy was 83% effective in preventing lung infections (like pneumonia) due to RSV during the first RSV season after vaccination. During the second RSV season after vaccination, one dose of Arexvy was still 56% effective against lung infections.
• In adults ages 60 years and older with healthy immune systems, one dose of the RSV vaccine Abrysvo was 89% effective in preventing lung infections (like pneumonia) due to RSV during the first RSV season after vaccination. Based on early results from the second RSV season in a large study of how well the vaccine works, Abrysvo continues to provide protection, but the second season is ongoing and final results have not yet been released.

What are the possible side effects?

Side effects such as pain, redness, and swelling where the shot is given, fatigue, fever, headache, nausea, diarrhea, and muscle or joint pain are possible after RSV vaccination. These side effects are usually mild. Patients who have experienced these symptoms when getting other vaccines might be more likely to experience them after RSV vaccination.

A small number of participants in clinical trials developed serious neurologic conditions, including Guillain-Barré syndrome (GBS), after RSV vaccination. GBS is a rare condition in which your immune system attacks your nerves, causing symptoms such as weakness. However, given the small number, it is unclear whether the vaccine caused these events, or whether they occurred due to chance.

If you experience side effects from RSV vaccination, you should report them to the Vaccine Adverse Event Reporting System (VAERS). Your health care provider might file this report, or you can do it yourself through the VAERS website, or by calling 1-800-822-7967.

If you have any questions about side effects from RSV vaccination, talk with your health care provider.

When should I get an RSV vaccine?

For the 2023-24 RSV season, if you are 60 years or older and your health care provider recommends RSV vaccination for you, you should get an RSV vaccine as soon as it is available in your community, before the number of cases of RSV start to increase, which is usually in the fall and winter. Early vaccination will ensure you are protected by the time RSV begins to circulate in your community. During the 2021-22 and 2022-23 RSV seasons, the number of cases began increasing as early as July in parts of the United States, so it may be difficult to predict when it will start in 2023.

CDC recommends two ways to protect babies from getting very sick with Respiratory Syncytial Virus (RSV):

• An RSV vaccination given during pregnancy
  Pfizer’s bivalent RSVpreF vaccine (Abrysvo) is recommended for use during pregnancy (maternal RSV vaccine). It is given during RSV season to people who are 32 through 36 weeks pregnant. Or,

• An RSV immunization given directly to infants and some older babies

Babies born to mothers who get RSV vaccine at least 2 weeks before delivery will have protection and, in most cases, should not need an RSV immunization later.

When is RSV season?

In most regions of the United States RSV season starts in the fall and peaks in the winter, but the timing and severity of RSV season can vary from place to place and year to year. RSV season is likely to be different for people living in Alaska, parts of Florida, Hawaii, Puerto Rico, US Virgin Islands, Guam, and the U.S.-affiliated Pacific Islands.

The goal of maternal RSV vaccination is to protect babies from getting very sick with RSV during their first RSV season. In most of the continental United States, this means maternal RSV vaccine will be given in September through January.

If you live in Alaska, Florida, or outside the continental U.S., talk to your healthcare provider about when RSV season is expected where you live, so that your infant can be protected against RSV disease.

Who should get the maternal RSV vaccine?

People who are 32 through 36 weeks pregnant during September through January should get one dose of maternal RSV vaccine to protect their babies. RSV season can vary around the country. If you live in Alaska, Florida, or outside the continental U.S., talk to your healthcare provider about when RSV season is expected where you live.

How is the maternal RSV vaccine administered?

Maternal RSV vaccine is given as a shot into the mother’s upper arm. Only a single dose (one shot) of maternal RSV vaccine is recommended. It is not yet known whether another dose might be needed in later pregnancies.

How well does the maternal RSV vaccine work?

When someone gets RSV vaccine, their body responds by making a protein that protects against the virus that causes RSV. The process takes about 2 weeks. When a pregnant person gets RSV vaccine, their protective proteins (called antibodies) also pass to their baby. So, babies who are born at least 2 weeks after their mother gets RSV vaccine are protected at birth, when infants are at the highest risk of severe RSV disease. The vaccine can reduce a baby’s risk of being hospitalized from RSV by 57% in the first six months after birth.

What are the possible side effects of the maternal RSV vaccine?

In the clinical trials, the side effects most often reported by pregnant people who received the maternal RSV vaccine were pain at the injection site, headache, muscle pain, and nausea.

Although not common, a dangerous high blood pressure condition called pre-eclampsia occurred in 1.8% of pregnant people who received the maternal RSV vaccine compared to 1.4% of pregnant people who received a placebo.

The clinical trials identified a small increase in the number of preterm births in vaccinated pregnant people. It is not clear if this is a true safety problem related to RSV vaccine or if this occurred for reasons unrelated to vaccination.

To reduce the potential risk of preterm birth and complications from RSV disease, FDA approved the maternal RSV vaccine for use during weeks 32 through 36 of pregnancy while additional studies are conducted.

FDA is requiring the manufacturer to do additional studies that will look more closely at the potential risk of preterm births and pregnancy-related high blood pressure issues in mothers, including pre-eclampsia.

Severe allergic reactions to vaccines are rare but can happen after any vaccine and can be life-threatening. If you see signs of a severe allergic reaction after vaccination (hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness, or weakness), seek immediate medical care by calling 911.  As with any medicine or vaccine there is a very remote chance of the vaccine causing other serious injury or death after vaccination.

Adverse events following vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS), even if it’s not clear that the vaccine caused the adverse event. You or your doctor can report an adverse event to CDC and FDA through VAERS. If you need further assistance reporting to VAERS, please email info@VAERS.org or call 1-800-822-7967.

If you have any questions about side effects from the maternal RSV vaccine, talk with your healthcare provider.

Do I need a prescription for a maternal RSV vaccine?

Depending on where you live and where you go to get the vaccine, you might need a prescription. See CDC’s Where to Find Vaccines for information on prescriptions for vaccines.

How do I pay for the maternal RSV vaccine?

Private health insurance

Most private health insurance plans cover the maternal RSV vaccine, but there may be a cost to you depending on your plan. Contact your insurer to find out.

Medicaid

Beginning October 1, 2023, most people with coverage from Medicaid and Children’s Health Insurance Program (CHIP) will be guaranteed coverage of all vaccines recommended by the Advisory Committee on Immunization Practice at no cost to them.

Vaccines for Children (VFC) program

The maternal RSV vaccine will be covered by VFC, a federally funded program that provides vaccines to children who otherwise might not be vaccinated because of inability to pay. Pregnant teens enrolled in Medicaid will not be charged for the vaccine or administration. VFC-eligible teens not enrolled in Medicaid will get the vaccine at no charge but may be charged an administration fee. Children younger than 19 years of age are eligible for the VFC Program if they belong to one or more of the following groups:

• Medicaid-eligible
• Uninsured
• Underinsured
• American Indian or Alaska Native

Why get immunized with a RSV preventive antibody?

A respiratory syncytial virus (RSV) preventive antibody can prevent severe lung disease caused by RSV.

RSV is a common respiratory virus that usually causes mild, cold-like symptoms but can also affect the lungs. Symptoms of RSV infection may include runny nose, decrease in appetite, coughing, sneezing, fever, or wheezing.

Anyone can become infected by RSV, and almost all children get an RSV infection by the time they are 2 years old. While most children recover from an RSV infection in a week or two, RSV infection can be dangerous for infants and some young children, causing difficulty breathing, low oxygen levels, and dehydration. In the United States, RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lungs) and pneumonia (infection of the lungs) in children younger than 1 year of age. Children who get sick from RSV may need to be hospitalized, and some might even die.

RSV Preventive Antibodies

The RSV preventive antibody (generic name nirsevimab, trade name Beyfortus) is a shot that prevents severe RSV disease in infants and young children. Antibodies are proteins that the body’s immune system uses to fight off harmful germs. Like traditional vaccines, preventive antibodies are immunizations that provide protection against a specific pathogen. While both are immunizations, the way they provide immunity is different. Nirsevimab is an immunization that provides antibodies directly to the recipient. Traditional vaccines are immunizations that stimulate the recipient’s immune system to produce antibodies.

Infants born during the RSV season (typically fall through spring) should receive a single dose of the RSV Immunization within 1 week after birth. Most infants whose mothers got the RSV vaccine don’t need to get nirsevimab, too. Both protect infants from severe RSV by providing antibodies, either from the mother to the infant or directly to the infant. Most infants will likely only need protection from either the maternal RSV vaccine or nirsevimab (not both). However, there may be some situations in which nirsevimab would be recommended for an infant after the mother received an RSV vaccine.

Infants born outside of the RSV season who are younger than 8 months should receive a single dose of the RSV Immunization shortly before their first RSV season (typically the fall), but infants who are younger than 8 months who have not yet received a dose may receive a dose at any time during the season.

Some infants and young children who are at increased risk for severe RSV disease may need a single dose of the RSV antibody before or during their second RSV season.

RSV preventive antibodies can be given at the same time as vaccines routinely recommended for infants and young children.

Talk with your health care provider

Tell your health care provider if the person getting the preventive antibody has a:

• History of serious allergic reactions to an RSV preventive antibody (nirsevimab) or any of its components,
• Bleeding disorder, or
• Moderate or severe acute illness.

In some cases, your child’s health care provider may decide to postpone giving RSV preventive antibodies until a future visit.

People who have a minor illness, such as a cold, can safely receive an RSV preventive antibody. People who are moderately or severely ill should usually wait until they recover.

Your health care provider can give you more information.

Risks of a reaction to RSV preventive antibodies

After getting an RSV preventive antibody, your child might have temporary pain, redness, swelling where the injection was given, or a rash.

As with any medicine, there is a very remote chance that RSV Immunization could cause a severe allergic reaction, other serious injury, or death.

An allergic reaction could occur after your child leaves the hospital or clinic. If you see signs of a severe allergic reaction (for example, hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness, or weakness), call 9-1-1 and get your child to the nearest hospital.

Call your health care provider if you see any other symptoms that concern you.

What if there is a serious problem?

If your child got an RSV preventive antibody without getting a vaccine at the same time, and you suspect an adverse reaction, you or your health care provider can submit a report through https://www.fda.gov/medwatch or by phone at 1-800-FDA-1088.

If your child got an RSV preventive antibody and a vaccine at the same time and you suspect an adverse reaction, you or your health care provider should report it to the Vaccine Adverse Event Reporting System (VAERS) https://vaers.hhs.gov/ or call 1-800-822-7967. In your report, note that your child got an RSV Immunization along with a vaccine.

Note: MedWatch and VAERS are only for reporting reactions. MedWatch and VAERS staff members do not give medical advice.

Why get vaccinated?

RSV vaccine can prevent lower respiratory tract disease caused by respiratory syncytial virus (RSV). RSV is a common respiratory virus that usually causes mild, cold-like symptoms.

RSV is usually spread through direct contact with the virus, such as droplets from another person’s cough or sneeze contacting your eyes, nose, or mouth. It can also be spread by touching a surface that has the virus on it, like a doorknob, and then touching your face before washing your hands.

RSV can cause illness in people of all ages but may be especially serious for infants and older adults. Infants and older adults with chronic medical conditions like heart or lung disease, weakened immune systems, or who live in nursing homes or long-term care facilities, are at highest risk of serious illness and complications from RSV.

Symptoms of RSV infection may include runny nose, decrease in appetite, coughing, sneezing, fever, or wheezing. Most people recover in a week or two, but RSV can be serious, resulting in shortness of breath and low oxygen levels. RSV can also sometimes lead to worsening of other medical conditions such as asthma, chronic obstructive pulmonary disease (a chronic disease of the lungs that makes it hard to breathe), or congestive heart failure (when the heart can’t pump enough blood and oxygen through the body).

Older adults and infants who get very sick from RSV may need to be hospitalized. Some may even die.

RSV vaccine

CDC recommends adults 60 years and older may receive a single dose of RSV vaccine, based on discussions between the patient and health care provider. 

RSV vaccine may be given at the same time as other vaccines.

Talk with your health care provider

Tell your vaccination provider if the person getting the vaccine:

• Has had an allergic reaction after a previous dose of RSV vaccine, or has any severe, life-threatening allergies

In some cases, your health care provider may decide to postpone RSV vaccination until a future visit.

People with minor illnesses, such as a cold, may be vaccinated. People who are moderately or severely ill should usually wait until they recover before getting RSV vaccine.

Your health care provider can give you more information.

Risks of a vaccine reaction

• Pain, redness, and swelling where the shot is given, fatigue (feeling tired), fever, headache, nausea, diarrhea, and muscle or joint pain can happen after RSV vaccination.

Serious neurologic conditions, including Guillain-Barré syndrome (GBS), have been reported very rarely after RSV vaccination in clinical trials. It is unclear whether the vaccine caused these events.

People sometimes faint after medical procedures, including vaccination. Tell your provider if you feel dizzy or have vision changes or ringing in the ears.

As with any medicine, there is a very remote chance of a vaccine causing a severe allergic reaction, other serious injury, or death.

What if there is a serious problem?

An allergic reaction could occur after the vaccinated person leaves the clinic. If you see signs of a severe allergic reaction (hives, swelling of the face and throat, difficulty breathing, a fast heartbeat, dizziness, or weakness), call 9-1-1 and get the person to the nearest hospital.

For other signs that concern you, call your health care provider.

Adverse reactions should be reported to the Vaccine Adverse Event Reporting System (VAERS). Your health care provider will usually file this report, or you can do it yourself. Visit the VAERS website or call 1-800-822-7967. VAERS is only for reporting reactions, and VAERS staff members do not give medical advice.

What is the difference between nirsevimab and a traditional vaccine?

Nirsevimab (Beyfortus) is a long-acting monoclonal respiratory syncytial virus (RSV) antibody that prevents severe RSV disease. Although both monoclonal antibodies and vaccines provide protection through immunization, the way they provide immunity is different. Nirsevimab provides RSV antibodies directly to the recipient (passive immunization) while vaccines stimulate the recipient’s immune system, including production of antibodies (active immunization).

Nirsevimab Indication, Dosage and Schedule

Who is recommended to receive nirsevimab?

Nirsevimab is recommended for infants younger than age 8 months who are born shortly before or are entering their first RSV season (typically fall through spring) if

• The mother did not receive RSV vaccine during pregnancy.
• The mother’s RSV vaccination status is unknown.
• The infant was born within 14 days of maternal RSV vaccination.

Except in rare circumstances, nirsevimab is not needed for most infants younger than age 8 months who are born 14 or more days after their mother received RSV vaccine during pregnancy (see section on special population and situations).

A dose of nirsevimab is also recommended for some children aged 8 through 19 months who are at increased risk for severe RSV and who are entering their second RSV season. The following children aged 8 through 19 months are recommended to get a dose when entering their second RSV season:

• Children with chronic lung disease of prematurity who required medical support (chronic corticosteroid therapy, diuretic therapy, or supplemental oxygen) any time during the 6-month period before the start of the second RSV season
• Children with severe immunocompromise
• Children with cystic fibrosis who have either 1) manifestations of severe lung disease (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest imaging that persist when stable), or 2) weight-for-length 10th percentile
• American Indian or Alaska Native children

Children aged 8 months and older who do not meet any of the criteria listed above are not recommended to receive nirsevimab.

Can children at increased risk for severe RSV disease receive nirsevimab during their first RSV season if 8 through 11 months?

Children at increased risk for severe RSV disease can receive nirsevimab during their first RSV season if 8 through 11 months. For example, an infant at increased risk for severe RSV disease who was born in April and who did not receive nirsevimab until December (at 8 months of age), nirsevimab is recommended.  Although optimal timing of administration is just before the start of the RSV season, nirsevimab may be administered until the end of the RSV season if nirsevimab had not been given during that season.

Children at increased risk for severe RSV disease are recommended to receive nirsevimab if all the following apply:

• They are younger than age 20 months on the day of immunization
• The day of immunization is either shortly before or during RSV season (typically October through March for most of the continental United States)
• They have not previously received a total of two doses of nirsevimab. Only one dose is recommended each RSV season except for children undergoing cardiac surgery with cardiopulmonary bypass label (fda.gov)
• They meet at least one of the following criteria:
  • Chronic lung disease of prematurity who required medical support (chronic corticosteroid therapy, diuretic therapy, or supplemental oxygen) any time during the 6-month period before the start of the RSV season
  • Severe immunocompromise
  • Cystic fibrosis who have either
    • Manifestations of severe lung disease (previous hospitalization for pulmonary exacerbation in the first year of life or abnormalities on chest imaging that persist when stable)
      Or
    • Weight-for-length 10th percentile
  • American Indian and Alaska Native children

For children ages 8 through 19 months who are recommended to receive nirsevimab during their second RSV season, what is the minimum interval between doses given in first and second RSV season?

Only one dose of nirsevimab is recommended for each season. Each dose of nirsevimab provides protection for at least 5 months, and a second dose of nirsevimab is not recommended to be given within 5 months of the first dose.

Can I give nirsevimab to children ages 20 months and older who at increased risk for severe RSV disease?

Nirsevimab is not recommended for any child who is age 20 months and older. Children ages 20 months and older have likely already experienced two RSV seasons and been infected with RSV, and thus are less likely to benefit from nirsevimab.

Do the recommended ages for nirsevimab refer to the age at time of immunization?

Yes, the child‘s age on the day nirsevimab is administered should be used to determine if the child is eligible for immunization. For example, a healthy child who was aged 8 months at the beginning of the RSV season but did not receive nirsevimab and is now aged ≥8 months and whose family is requesting nirsevimab during the RSV season is not recommended to receive nirsevimab.

What is the recommended dose of nirsevimab?

• Age less than 8 months
  • 50 mg for infants weighing 5 kg [11 lb]
  • 100 mg for infants weighing ≥5 kg [≥ 11 lb]
• Age 8 through 19 months:
  • 200 mg, administered as two 100 mg injections

Are there any contraindications/precautions for nirsevimab?

Nirsevimab is contraindicated in children and infants with a history of severe allergic reaction (e.g., anaphylaxis) after a previous dose of nirsevimab or to a product component.

While neither a contraindication nor a precaution, nirsevimab should be used with caution in infants and children with bleeding disorders. Use a 23-gauge or smaller caliber needle and steady pressure to the site for 1-2 minutes.

In accordance with CDC General Best Practice Guidelines for Immunization, children who have a moderate or severe acute illness should usually wait until they recover before getting nirsevimab.

Timing of Nirsevimab Administration

What time of the year should I give nirsevimab?

While the timing of the onset and duration of RSV season may vary, nirsevimab may be administered October through the end of March in most of the continental United States. The timing of the onset, peak, and decline of RSV activity vary geographically, and providers may adjust timing of administration based on guidance from public health authorities (e.g., CDC, health departments) or regional medical centers. For example, health care providers in areas with known early RSV transmission may choose to begin administration of nirsevimab before October (e.g., Florida). Although optimal timing of administration is just before the start of the RSV season, nirsevimab may also be administered during the RSV season to infants and children who are age-eligible.

Potential administration timing for most of the continental United States during a typical RSV season (e.g., an RSV season that follows seasonality seen prior to the COVID-19 pandemic).

Providers should use every opportunity to administer nirsevimab to eligible infants. This includes administration during well-child visits as well as other visits to ensure no missed opportunities for immunization.

Tropical climates may have RSV circulation patterns that differ from most of the continental United States or are unpredictable. Locations with tropical climates include southern Florida, Hawaii, Guam, Puerto Rico, US Virgin Islands, and US-Affiliated Pacific Islands. In Alaska, RSV circulation patterns are less predictable, and the duration of RSV season is often longer than the national average. Providers in these jurisdictions should consult state, local, or territorial guidance on timing of nirsevimab administration.

How do you define if an infant is born during or entering their first RSV season?

Infants are recommended for nirsevimab if they meet the following criteria:

• They are aged 8 months on the day of administration.
• Either mother did not receive RSV vaccine during pregnancy more than 14 days prior to birth OR maternal RSV vaccine status is unknown
• The day of immunization is shortly before or during RSV season (typically October through March for most of the continental United States)
• They have not received a previous dose of nirsevimab during that RSV season

Because the risk of severe disease is highest during the first months after birth, nirsevimab is recommended within 1 week of birth for infants born shortly before or during the RSV season (typically October through March for most of the continental United States).

All infants aged 8 months at the time of immunization who have not received a dose of nirsevimab are recommended to receive nirsevimab when entering the RSV season, including those who may have been born towards the end of the previous RSV season.

Can nirsevimab be given before the beginning of RSV season?

Healthcare providers may choose to give nirsevimab before the start of RSV season (typical season begins October in most of the continental United States) if they feel that the child may not return for a visit when nirsevimab would be recommended. For example, a clinician may choose to give nirsevimab to an infant who presented for care in September who has not yet received a dose of nirsevimab and may be unlikely to return for a visit in October or November. Nirsevimab has been shown to protect against severe RSV disease for at least 5 months, and the ideal timing of administration may differ depending on the clinical situation.

Nirsevimab and RSV infection

How long after a child has RSV infection should I wait to give nirsevimab?

Nirsevimab recommendations are the same regardless of prior RSV infection or RSV-associated hospitalization. Reinfection with RSV, even during the same season, can occur. Children who are moderately or severely ill with or without fever including those who have known current RSV infection should defer nirsevimab until recovery from the acute illness.

Does nirsevimab interfere with RSV Diagnostic Tests?

Nirsevimab does not interfere with rapid antigen detection RSV diagnostic assays or reverse transcriptase polymerase chain reaction (RT-PCR) that employ commercially available antibodies targeting antigenic site I, II, or IV on the RSV fusion (F) protein. When clinical observations are consistent with RSV infection and immunological assay results are negative, it is recommended to confirm using an RT-PCR-based assay.

Nirsevimab and Routine Childhood vaccines

Can I give nirsevimab with routine childhood vaccines?

Yes. In accordance with CDC General Best Practice Guidelines for Immunization, simultaneous administration of nirsevimab with age-appropriate vaccines is recommended. Nirsevimab is not expected to interfere with the immune response to other vaccines. On the basis of limited data from clinical trials, coadministration of nirsevimab with routine vaccines resulted in a similar rate of adverse events compared with administration of vaccines alone.

Special Populations and Situations

Can nirsevimab be administered to infants whose mothers received RSV vaccination 14 or more days before birth?

Except in rare circumstances, nirsevimab is not needed for most infants younger than age 8 months who are born 14 or more days after their mother received RSV vaccine.

Nirsevimab can be considered in rare circumstances when the healthcare provider believes the potential benefit of giving it is warranted. These circumstances include, but are not limited to:

• Infants born to pregnant people who may not mount an adequate immune response to RSV vaccination (e.g., people with immunocompromising conditions)
• Infants born to pregnant people who have medical conditions associated with reduced transplacental antibody transfer (e.g., people living with HIV infection)
• Infants who have undergone cardiopulmonary bypass or extracorporeal membrane oxygenation (ECMO), leading to loss of maternal antibodies
• Infants with substantial increased risk for severe RSV disease (e.g., hemodynamically significant congenital heart disease, intensive care admission with a requirement of oxygen at discharge)

Is it safe for a baby to receive nirsevimab if their mother received the RSV vaccine?

There are no studies of infants who have been given nirsevimab after their mother received an RSV vaccine. However, the available evidence does not suggest a higher risk for adverse events in that situation. Children and adults (including pregnant people) are frequently exposed to circulating RSV viruses. Following RSV infection, pregnant people produce antibodies that are transferred to infants across the placenta, and many of the babies in the nirsevimab study had maternal RSV antibody. CDC and FDA will monitor safety of both products.

What is the recommendation for using nirsevimab in preterm infants?

In accordance with, General Best Practice Guidelines for Immunization preterm infants (infants born before 37 weeks’ gestation), regardless of birth weight, should receive nirsevimab at their chronological age using the same guidance for full-term infants and young children.

Preterm infants discharged from the hospital during the RSV season, including those with prolonged birth hospitalizations, should receive nirsevimab shortly before or promptly after discharge.

Can I give nirsevimab and palivizumab during the same RSV season?

Because a single dose of nirsevimab provides protection for 5 months, children who received nirsevimab should not receive palivizumab during the same RSV season.

Additional information on considerations for 2023-24 RSV season regarding palivizumab and nirsevimab administration to high-risk infants during the same RSV season is provided by the American Academy of Pediatrics.

What is the guidance for immunizing children undergoing cardiac surgery with cardiopulmonary bypass?

Children undergoing cardiac surgery with cardiopulmonary bypass should receive an additional dose of nirsevimab after surgery during RSV season if age-eligible. label (fda.gov)

First RSV season:

• If cardiac surgery with cardiopulmonary bypass is performed within 90 days after receiving nirsevimab, give an additional dose based on body weight at the time of the additional dose (50mg if less than 5kg and 100mg if 5kg or greater).
• If cardiac surgery with cardiopulmonary bypass is performed more than 90 days after receiving nirsevimab, give an additional dose of 50 mg regardless of body weight.

Second RSV season:

• If cardiac surgery with cardiopulmonary bypass is performed within 90 days after receiving nirsevimab, give an additional dose of 200 mg regardless of body weight.
• If cardiac surgery with cardiopulmonary bypass is performed more than 90 days after receiving nirsevimab, give an additional dose of 100 mg regardless of body weight.

Adverse Events After Nirsevimab Administration

Where can I report adverse events (side effects) that occur after receipt of nirsevimab?

Adverse reactions might occur after administration of nirsevimab alone; these reactions may be reported to MedWatch online (https://www.fda.gov/medwatch), by fax, by mail, or by contacting FDA at 1-800-FDA-1088.

Adverse reactions might occur after the coadministration of nirsevimab with a vaccine; these reactions should be reported to the Vaccine Adverse Event Reporting System (VAERS), and reports should specify that the patient received nirsevimab on the VAERS form Specifically, in Section 9: “Prescriptions, over-the-counter medications, dietary supplements, or herbal remedies being taken at the time of vaccination.” Reports can be submitted to VAERS online, by fax, or by mail. Additional information about VAERS is available by telephone (1-800-822-7967) or online (https://vaers.hhs.gov). When adverse reactions that occur after the coadministration of nirsevimab with a vaccine are reported to VAERS, additional reporting of the same adverse reactions to MedWatch is not necessary.

Two Respiratory Syncytial Virus (RSV) vaccines are approved for people ages 60 years and older.

• Arexvy (GSK adjuvanted RSV vaccine)
• Abrysvo (Pfizer RSV vaccine)

CDC recommends that adults ages 60 years and older may receive RSV vaccination, using shared clinical decision-making (SCDM). This means that health care providers should talk to these individuals about whether RSV vaccination is appropriate for them.

Is RSV an important cause of disease among older adults?

RSV is a common cause of respiratory illness in infants and young children, as well as older adults. Each season, RSV causes substantial morbidity and mortality in older adults, including lower respiratory tract disease, hospitalization, and death. There are an estimated 60,000–160,000 hospitalizations and 6,000–10,000 deaths annually due to RSV among adults ages 65 years and older.

What vaccines are approved for prevention of RSV, and is there a difference between them?

There are two RSV vaccines approved for adults ages 60 years and older – RSVPreF3 (Arexvy, GSK) and RSVpreF (Abrysvo, Pfizer). Both vaccines are recombinant protein vaccines that cause the immune system to produce RSV antibodies. Both are currently approved as a single dose and were shown in clinical trials protect against symptomatic lower respiratory tract disease caused by RSV in adults ages 60 and older, with more than 80% percent efficacy in the first RSV season after vaccination. GSK’s vaccine includes an adjuvant (the same adjuvant used in GSK’s recombinant zoster vaccine [Shingrix]), which is a component that is intended to enhance the immune response to vaccination. Pfizer’s vaccine does not contain an adjuvant. CDC does not have a preferential recommendation for either vaccine. Patients who are 60 years and older may receive whichever vaccine is available.

What does it mean to use a shared clinical decision-making (SCDM) recommendation for RSV vaccine?

CDC recommends that older adults ages 60 years and older may receive a single dose of RSV vaccine using SCDM. A SCDM recommendation differs from routine age-based and risk-based vaccine recommendations for which the default decision is to vaccinate all persons in a specified age group or risk group. With a SCDM recommendation, there is no group in which the vaccine is universally recommended. Rather, the decision to vaccinate a patient is based on individual health characteristics and informed by discussions between the patient and health care provider (anyone who provides or administers vaccines, including primary care physicians, specialists, physician assistants, nurse practitioners, registered nurses, and pharmacists). Health care providers may consider multiple factors when discussing RSV vaccination with patients, including whether the patient has any risk factors for severe RSV disease, the safety profile of the RSV vaccine products, a patient’s preferences for RSV vaccination, and the clinical discretion of the health care provider in that patient’s case.

Which adults are most likely to benefit from RSV vaccination?

Although RSV infection generally causes mild upper respiratory disease in healthy adults, RSV can cause serious illness in adults with certain underlying medical conditions or other risk factors. Adults ages 60 years and older who are at higher risk for severe RSV disease include:

• those with chronic medical conditions such as:
  • lung diseases (e.g., chronic obstructive pulmonary disease, asthma)
  • cardiovascular diseases (e.g., congestive heart failure, coronary artery disease)
  • neurologic or neuromuscular conditions
  • kidney disorders
  • liver disorders
  • hematologic disorders
  • diabetes mellitus
  • moderate or severe immune compromise (either attributable to a medical condition or receipt of immunosuppressive medications or treatment)
• those who are frail
• those of advanced age
• those who reside in nursing homes or other long-term care facilities
• those with other underlying medical conditions or factors that a health care provider determines might increase the risk of severe respiratory disease

What should I tell patients about the side effects of RSV vaccine?

The most common side effects after RSV vaccination reported from clinical trials included pain, redness, and swelling where the shot is given, fatigue, fever, headache, nausea, diarrhea, and muscle or joint pain. These side effects were usually mild.

Serious neurologic events, including Guillain-Barré syndrome (GBS) and other inflammatory neurologic events, were reported after RSV vaccination in clinical trials. Whether these events occurred due to chance or whether RSV vaccination increases the risk for inflammatory neurologic events is currently unknown. Until additional evidence is available to clarify the risk of inflammatory neurologic events after vaccination, RSV vaccination in older adults should be directed to those who are at highest risk for severe RSV disease and therefore most likely to benefit from vaccination. As for all FDA-approved vaccines, CDC will conduct post-marketing safety surveillance to further inform RSV vaccine recommendations.

How should I administer RSV vaccine?

You should administer either Arexvy (GSK adjuvanted RSV vaccine) or Abrysvo (Pfizer RSV vaccine) intramuscularly in the deltoid region of the upper arm with a 1- to 1.5-inch needle. For additional information on vaccine administration, see job aid on giving intramuscular vaccines to adults.

Do I need to reconstitute RSV vaccine?

Yes. Guidance below summarizes the preparation for both Arexvy (GSK adjuvanted RSV vaccine) or Abrysvo (Pfizer RSV vaccine). After reconstitution, both vaccines should be discarded if not used within 4 hours.

• Arexvy (GSK)
  • Prepare by reconstituting the lyophilized antigen component (a sterile white powder) with the accompanying adjuvant suspension component (an opalescent, colorless to pale brownish sterile liquid). The reconstituted vaccine should be an iridescent, colorless to pale brownish liquid. Either administer Arexvy immediately or store protected from light in the refrigerator (36°F to 46°F [2°C to 8°C]) or at room temperature up to 77°F (25°C) and use within 4 hours. Do not freeze reconstituted vaccine. Package Insert – AREXVY (fda.gov)

• Abrysvo (Pfizer)
  • Prepare by reconstituting the lyophilized antigen component (a sterile white powder) with the accompanying prefilled syringe containing sterile water diluent component. Either administer Abrysvo immediately or store at room temperature at 59°F to 86°F (15°C to 30°C) and use within 4 hours. Do not freeze reconstituted vaccine; do not store reconstituted vaccine under refrigerated conditions (36°F to 46°F [2°C to 8°C]). Use within 4 hours. Package Insert – ABRYSVO (fda.gov)

Where should I store RSV vaccine?

Storage for Arexvy (GSK adjuvanted RSV vaccine) and Abrysvo (Pfizer RSV vaccine) is as follows:

• Arexvy
  • Arexvy adjuvant suspension component vial and lyophilized antigen component vials must be refrigerated in the original package at temperature of 36°F to 46°F (2°C to 8°C). Protect vials from light. Do not freeze. Discard if the adjuvant suspension component or antigen component has been frozen.

• Abrysvo
  • Abrysvo kit (vial of lyophilized antigen component [a sterile white powder] and prefilled syringe containing sterile water and diluent component) must be refrigerated at 36°F to 46°F (2°C to 8°C) in the original carton. Do not freeze. Discard if any component has been frozen.

How many doses of RSV vaccine do I give?

So far, RSV vaccines appear to provide some protection for at least two RSV seasons. Additional surveillance and evaluation activities are planned to assess how long the vaccines protect against RSV and whether additional doses will be needed.

What is the best time of year to give RSV vaccine?

Optimally, vaccination should occur before the onset of the fall and winter RSV season. However, typical RSV seasonality was disrupted by the COVID-19 pandemic and has not returned to pre-pandemic patterns. For the 2023–24 RSV season, providers recommending RSV vaccine based on SCDM should administer RSV vaccine as early as vaccine supply becomes available.

Can I give RSV vaccine with other adult vaccines?

Administration of RSV vaccine on the same day with other adult vaccines is acceptable. However, according to results of coadministration studies of RSV vaccines with influenza vaccines, common side effects, such as fever and soreness at the injection site, may be increased when these two vaccines are administered on the same day. Some studies also suggest it’s possible that the RSV and flu vaccines may not produce as strong of an immune response if they’re given on the same day, but the clinical significance of this is unknown. Additional research is ongoing to further inform guidance on same-day administration of the RSV vaccine and other adult vaccines, including the COVID-19 vaccine.

Respiratory syncytial virus (RSV) is a common respiratory virus that usually causes mild, cold-like symptoms. However, RSV can cause serious illness or death in premature or very young infants and people over age 65, highlighting a critical need for vaccines in these populations.

Journey to a Better Vaccine

After NIH scientists identified RSV as a human pathogen in 1957, researchers tested multiple vaccines that proved unsuccessful, leading scientists to explore RSV surface proteins as a vaccine target for pregnant people (to protect the newborn) and the elderly.

• 1980s

  Scientists identified the RSV fusion “F” protein,a surface protein that helps the virus infect human cells.

• 1990s

  NIAID researchers found mice exposed to the RSV F protein produced a more protective immune response compared to mice exposed to other surface proteins.

• 2000s

  Two formsof the RSV F protein were identified, later determined to be the prefusion and postfusion states.

• 2010s

  NIAID scientists locked the RSV F protein in its prefusion state, which was a more protective vaccine candidate.

• 2020s

  Vaccine candidates using the locked RSV prefusion F proteinbegan Phase 3 clinical trials.

Two States of the RSV F Protein

Preclinical Findings Show Promise for Prefusion F Protein Vaccines

NIAID found animals vaccinated with prefusion F protein developed a more potent immunity than those vaccinated with the postfusion F protein. This discovery led scientists toward finding a way to prevent the F protein from transitioning from its prefusion state to its postfusion state.

NIAID Scientific Breakthrough: Stabilized Prefusion F Protein

First FDA-Approved RSV Vaccine for Special Populations

The locked (i.e., stabilized) prefusion F protein became a primary target for RSV protein vaccine development for pregnant people (to protect their newborn) and the elderly. In 2023, the FDA approved the first RSV stabilized prefusion F protein vaccine for use in special populations. Critical work is still needed to develop vaccines for those most affected by RSV, including infants and young children.