Respiratory Syncytial Virus (RSV) Vaccine

Learn about the options available to protect you and your baby from Respiratory Syncytial Virus (RSV).

  • RSV (Respiratory Syncytial Virus) is a common virus that causes respiratory infections. It spreads easily through droplets from coughing and sneezing.

  • The highest risk of severe RSV illness is during the first few months of life. Babies under six months are most vulnerable to serious complications from RSV.

  • As of June 2023, there are two ways to protect babies from severe RSV: the maternal RSVpreF vaccine given during pregnancy, or the RSV antibody for newborn babies given shortly after birth.

  • Choosing between the maternal RSVpreF vaccine or the infant RSV antibody depends on personal preference, availability in your province/territory, and cost.

Protecting Against RSV

Respiratory Syncytial Virus (RSV) is a common and very contagious virus that can be serious for babies. Approximately 20 to 30% of babies who catch RSV will develop serious infections like bronchiolitis (inflammation of the small airways) or pneumonia (infection of the lungs).1-3

There are currently two options available to protect babies from getting very sick with RSV:

  1. Maternal RSV Vaccine (RSVpreF)

    This vaccine is recommended between 32 and 36 weeks of pregnancy. It was specifically designed for use during pregnancy and tested among pregnant individuals worldwide.4

  2. Infant RSV Antibody (Nirsevimab)

    This monoclonal antibody contains pre-made antibodies and is given to babies as a single shot shortly after they are born.4

You can choose to get the RSVpreF vaccine during pregnancy OR your baby can receive Nirsevimab soon after birth. Both options safe and effective in protecting babies against severe illness and hospitalization from RSV. Choosing between the maternal RSVpreF vaccine or the infant antibody depends on your personal preferences, what's available in your province or territory, and cost.

About RSV

Respiratory syncytial virus (RSV) is a seasonal virus that spreads easily and causes millions of infant hospitalizations and about 120,000 deaths worldwide among children under five each year.⁵

RSV is especially dangerous for babies in their first 6 months of life.²˒⁶ A study on RSV hospitalizations in children’s hospitals across Canada found:

  • Half of all RSV hospitalizations were in babies under 6 months old.²

  • Nearly 40% of RSV hospitalizations were in babies between 0 and 2 months old.²

  • About 60% of babies needing intensive care were between 0-5 months old.²

RSV infections typically start with symptoms like a runny nose, dry cough, low-grade fever, sore throat, and sneezing. In young babies, RSV can lead to more severe illnesses like bronchiolitis (inflammation of the small airways in the lungs) and pneumonia. Babies with bronchiolitis or pneumonia often have a severe cough, wheezing, and difficulty breathing.

  • When someone with RSV coughs or sneezes, they release tiny droplets containing the virus into the air. If you breathe in these droplets, you can get infected with RSV.

    Additionally, you can catch RSV through direct contact with a surface that the virus has contaminated, and then touching your face (eyes, mouth, and nose) before washing your hands. You can also get infected by kissing the face of a child with RSV.

  • Young babies under six months old are at a higher risk of getting sick from RSV and may need to go to the hospital. Although the risk decreases after the first six months of life, severe RSV infections can still occur later.4

    Serious complications of RSV include:

    • Pneumonia (infection of the lungs)

    • Bronchitis or bronchiolitis (inflammation of the small airways in the lungs)

    • Apnea (slow or stopped breathing)

    Unfortunately, some babies may become so sick with RSV that they can die. Most of these cases involve babies under three months old.1, 7 Babies who are born prematurely or who have lung, heart diseases, or Down Syndrome are at an even higher risk of RSV complications.1

  • During pregnancy, your body goes through many changes to nourish a growing baby. You are now breathing for two and pumping blood for two. Your lungs and heart are working harder to make sure you and your baby both get what you need. These changes can make it harder for your body to fight infections. All respiratory infections during pregnancy can cause complications for you and for your developing baby even if you are otherwise healthy.

    There are only a few reports of severe RSV infections during pregnancy that require hospital or intensive care.8 We have limited information on how often pregnant people get RSV and how serious it can be. This is partly because, until recently, doctors didn't routinely test pregnant people with respiratory infections to identify the specific germ causing the illness.

  • RSV is very common. In Canada, most RSV infections occur between the fall and the early spring.

    • RSV is the main cause of serious lung infections like pneumonia and bronchiolitis in infants and young children.1

    • Approximately 20 to 30% of babies who catch RSV will develop bronchiolitis (inflammation of the small airways) or pneumonia (infection of the lungs).1

    • Nearly 1 in 4 children and adolescents with RSV end up in an intensive care unit (ICU).2

    • Over 60% of all RSV-related ICU admissions are in babies between 0 and 5 months old.2

  • Since 2023, there are two ways to protect young babies from severe illness and hospitalization with RSV:

    • The maternal RSV vaccine (RSVpreF) given to pregnant individuals between 32 and 36 weeks of pregnancy.

    • One dose of RSV antibodies (Nirsevimab) for newborns, also known as passive immunization with monoclonal antibodies.

    The choice between the maternal vaccine and the infant RSV antibody depends on your personal preferences, the availability of each product in your province or territory, and cost. Talk to your healthcare provider for more information on what's available in your province or territory.

About the Maternal RSV Vaccine (RSVpreF)

The maternal RSV vaccine (RSVpreF) was approved by Health Canada in 2023 to help prevent severe RSV infections in young babies. It is the only RSV vaccine approved for use during pregnancy in Canada.

The RSVpreF vaccine is recommended for pregnant people between 32 and 36 weeks of pregnancy. It protects against the two most common types of RSV in Canada and provides protection for your baby for up to 6 months after birth.⁴

RSVpreF was specifically designed for use during pregnancy and has been tested among pregnant people worldwide.

  • Think of vaccines as a way for your body's immune system to practice fighting off a germ without giving you an actual infection.

    • The RSVpreF vaccine works by showing your immune system a harmless piece of the RSV virus that is not alive. It contains proteins from the two most common types of RSV viruses (RSV-A and RSV-B).10

    • Within 2 weeks of getting the vaccine, your body makes protective antibodies and memory cells against RSV viruses A and B.

    • During pregnancy, these protective antibodies pass to your baby through the placenta. This gives them early protection against severe illness and hospitalization from RSV during the first few months of life, when they are at the highest risk of severe RSV.4

  • Think of the RSVpreF vaccine as a training session for your body’s immune system. It teaches your immune defences to recognize the RSV virus, without causing any illness.

    • The vaccine contains safe, harmless proteins from the two most common types of RSV viruses (RSV-A and RSV-B).10

    • When your body detects these proteins, it creates protective antibodies and memory cells, helping defend you against the real virus.

    • During pregnancy, these protective antibodies travel through the placenta to your baby, giving them early protection from RSV during their first few months of life—when they are most vulnerable to serious illness. Protective antibodies can also be passed through breastmilk.10

    • Only the protective antibodies reach your baby. The vaccine stays near the injection site (your arm muscle) and is gradually broken down and eliminated by your body over time.

    See video: How Vaccines Protect Moms and Babies

  • Getting the RSVpreF vaccine during pregnancy helps protect your baby from severe RSV illness in their first few months of life. This means that babies whose parent received the RSV vaccine during pregnancy can still get RSV, but if they do, the chances of them becoming seriously ill or needing to be hospitalized are much lower.

    The maternal RSVpreF vaccine has been shown to lower a baby’s risk of hospitalization from RSV by about 68% in the first three months after birth and about 57% within the first six months.4,10

    The vaccine is given to pregnant people between 32 and 36 weeks of pregnancy. After you get the vaccine, it takes about 2 weeks for your body to make protective antibodies that can be passed to your baby. That’s why it’s important to get the vaccine at least 2 weeks before your baby is born.

About the Infant RSV Antibody (Nirsevimab)

The RSV infant antibody (Nirsevimab) contains pre-made antibodies in a single shot given to babies shortly after birth. This type of protection is called passive immunization, where the body is given ready-made defences (antibodies) rather than having to produce them.

Nirsevimab works by attaching to the RSV virus and preventing it from entering your baby’s cells, stopping the virus from spreading and causing illness.9

Studies have shown that Nirsevimab protects babies from severe RSV illness and hospitalization for at least 5 months, which covers a typical RSV season.9 This early protection is crucial because babies are most vulnerable to severe RSV infections during their first few months of life.

  • The infant RSV antibody (Nirsevimab) contains pre-made antibodies and is given to babies as a single shot shortly after birth. Since these antibodies are already made, your baby doesn’t need to produce them on their own. This type of protection is known as passive immunization.

    Nirsevimab works by attaching to the RSV virus and blocking it from entering cells. It has been shown to protect babies from severe RSV illness and hospitalization for at least 5 months after birth, covering a typical RSV season.9

  • Nirsevimab provides pre-made antibodies, meaning your baby doesn’t need to make these antibodies themselves. This type of protection is called passive immunization, where the body is given ready-made defences (antibodies) rather than having to produce them.

    Once in the body, these antibodies attach to the RSV virus and block it from entering cells. By preventing the virus from getting inside cells, Nirsevimab stops RSV from spreading and causing illness. This helps protect your baby from serious RSV infections.

  • The infant RSV antibody helps protect babies from severe RSV illness. Babies who receive this immunization shortly after birth can still catch RSV, but the chances of them becoming seriously ill or needing to be hospitalized are much lower.

    While it doesn’t prevent all RSV infections, Nirsevimab lowers a baby’s risk of hospitalization from RSV by 80-90% in their first RSV season.4 Babies are protected as soon as they receive the shot.

    Nirsevimab has been shown to protect babies from severe RSV illness and hospitalization for at least 5 months after birth, covering the length of a typical RSV season.9

Babies under 6 months are most vulnerable to
severe complications from RSV.

Which Option is Best for Me and My Baby?

When choosing between the maternal RSVpreF vaccine and the infant RSV antibody (Nirsevimab), several factors may come into play, including personal preference, availability in your province or territory, and cost. Due to cost and supply limitations, Nirsevimab may not be available to all babies in the next few RSV seasons. In many cases, it may be reserved for babies at higher risk, such as those born prematurely (before 37 weeks), babies with lung or heart conditions, or those born in very remote areas.

Each option has its benefits, and the best choice for you and your baby may depend on your unique situation. It's a good idea to talk with your healthcare provider about the options available to you. They can offer information and guidance based on your health needs, preferences, and circumstances, helping you make the best decision for your family.

RSV Vaccine Safety

  • Yes, the inactivated RSV vaccine (RSVpreF)is safe for pregnant people and their developing babies. The vaccine uses an inactive (dead) piece of the RSV virus to teach your immune system to recognize and fight the real virus if you come into contact with it. This means the maternal RSV vaccine can't make you sick or cause any harm your baby because it does not contain a ‘live’ virus.

  • No, the RSVpreF vaccine approved for use during pregnancy does not increase the risk of complications for either pregnancy or birth. In fact, getting the maternal RSV vaccine helps protect both you and your baby by reducing the risk of severe RSV infections.

    The approval process for the maternal RSVpreF vaccine was unique because it included pregnant individuals in the clinical trials. This provides strong evidence that the vaccine is safe and effective during pregnancy.

    Here’s what the studies show:

    • In studies conducted in Argentina and South Africa, preterm births (babies born before 37 weeks) occurred in 5.6% of pregnant people vaccinated between 24 and 36 weeks of pregnancy, compared to 4.7% of those who did not get the vaccine.10-12

    • When the vaccine was given during the recommended period of 32 to 36 weeks of pregnancy, preterm births occurred in 4.2% of vaccinated pregnant people compared to 3.7% of those unvaccinated.10-12 These small differences were not statistically significant, meaning they could have happened by chance.

    • It's important to know that in Canada, up to 8% of babies are born prematurely, which is the typical rate for the general population. This means the rates of preterm birth seen in the study are actually lower than what we expect in real life.4

    • In regions like Canada, the US, and Europe, studies have shown no difference in the rate of preterm births between those who received the RSVpreF vaccine and those who didn’t.4,13

    • There is also no evidence that the RSVpreF vaccine affects future fertility or increases the risk of miscarriage.4,13

  • Neither you nor your baby can catch RSV from the maternal RSVpreF vaccine because it does not contain a live virus. The maternal RSVpreF vaccine recommended during pregnancy is inactivated, meaning it uses a harmless, non-living piece of the RSV virus (proteins) that can't make you or your baby sick.

    Similarly, there is no risk of getting RSV from the infant antibody (Nirsevimab) because it only contains antibodies that neutralize the virus, not the virus itself.

  • After getting the maternal RSVpreF vaccine, some people may feel tired or have soreness in the arm where the injection was given. These side effects usually last from a few hours to a couple of days and are normal signs that your body is building protection against RSV. Serious side effects are rare and typically limited to the injection site, such as soreness or tenderness in the muscle where the shot was given.4,10

    Studies of the maternal RSVpreF vaccine show that the most common side effects for pregnant individuals are redness or soreness at the injection site, muscle aches, and headaches.10,12 These symptoms are usually mild and go away on their own after a short time.10

    Similarly, the most common side effects of Nirsevimab are pain, redness, or swelling at the injection site.13,14 No serious allergic reactions were reported during the clinical trials.14

  • If you are sick and have a fever, it's better to wait until you feel better to get the maternal RSV vaccine. You should not get the maternal vaccine if you have had a severe allergic reaction, like anaphylaxis, to any component in the vaccine.

  • If your symptoms last longer than a couple of days, or if you are worried about how you feel after your vaccination, you can call your doctor or get help by calling the toll-free health information and advice phone service available in your province/territory:

    • British Columbia, Alberta, Saskatchewan, Ontario, Quebec, New Brunswick, Nova Scotia, Newfoundland and Labrador, New Brunswick, Prince Edward Island, the Yukon, the Northwest Territories: Call 811

    • Manitoba: Call 1-888-315-9257

    • Nunavut: Call 211

    You can also get help by visiting your nearest emergency department or urgent care centre. If you develop any serious symptoms that you think could be an allergic reaction after your vaccination, call emergency services right away by dialling 911.

RSV Vaccine Timing

  • The maternal vaccine is recommended between 32 and 36 weeks of pregnancy. It’s best to get the maternal RSVpreF vaccine soon before or during the RSV season. In Canada, the RSV season typically begins in late fall and lasts until spring, with most cases occurring between December through March. Talk with your healthcare provider for more information on when you can get the maternal RSV vaccine.

  • Yes! There is data available showing that you can safely get the maternal RSVpreF vaccine at the same time as the flu and Tdap vaccines.4,15 There is no data available yet on getting the maternal RSVpreF vaccine and COVID-19 vaccines together.4 Talk to your healthcare provider for more information on the best time to get vaccinated.

  • As of June 2024, only one dose (shot) of the maternal RSVpreF vaccine is recommended for pregnant people. Currently, there is not enough data to determine whether another dose might be needed in later pregnancies.4,14 The National Advisory Committee on Immunization (NACI) will continue to monitor the latest data and will update this recommendation once more information is available.

  • Yes, you can still get the maternal RSVpreF vaccine even if you've had an RSV infection before.4 Getting the vaccine boosts your immunity (protection) against RSV and helps make sure you and your baby are protected against future RSV infections.

Additional Information

  • The maternal RSVpreF vaccine is available at pharmacies. Pregnant individuals can check the maternal RSV website to find participating pharmacies (https://www.abrysvo.com/find-a-vaccine).

    As of June 2024, it's uncertain whether all Canadian provinces and territories will have the infant RSV antibody (Nirsevimab) available for the 2024 RSV season, or if it will be offered to all babies or only those at highest risk. Talk to your healthcare provider about RSV protection for your baby. They can advise you on the best options based on your baby's age, health, and the current availability of Nirsevimab.

  • Getting the maternal RSV vaccine during pregnancy or the infant RSV antibody for your baby are the best ways to protect against RSV infection. It’s also a good idea to keep small babies away from people who are sick and to encourage anyone in your household who is sick to cover their mouth when they cough or sneeze and to wash their hands regularly. If possible, breastfeed your baby, as breast milk contains antibodies that can help protect against RSV infection.

Both the maternal RSVpreF vaccine and the infant antibody help protect babies from severe illness and hospitalization.

Key Facts

  • RSV (Respiratory Syncytial Virus) is a common virus that causes respiratory infections. It spreads easily through droplets from coughing and sneezing.

  • RSV can be particularly serious for babies, especially those under 1 year of age, leading to severe respiratory illness and hospitalization.

  • The highest risk of severe RSV illness is during the first few months of life. Babies under 6 months are most vulnerable to serious complications from RSV.

  • As of June 2023, there are two ways to protect babies from severe RSV: the maternal RSV vaccine (RSVpreF) given during pregnancy or the infant RSV antibody (Nirsevimab) given to newborn babies after birth.

  • The choice between the maternal RSVpreF vaccine and the infant RSV antibody depends on personal preference, availability, and cost. Your healthcare provider can help you decide the best option for your baby.

  • The availability of the infant RSV antibody (Nirsevimab) varies by province/territory and may only be available for babies at higher risk. Check with your healthcare provider for more information on current options.

  • The maternal RSV vaccine is recommended between 32 and 36 weeks of pregnancy. Getting the maternal vaccine in pregnancy helps protect your baby for up to 6 months after they are born.

  • The infant RSV antibody (Nirsevimab) is a pre-made antibody given as a single shot to newborns, ideally soon after birth.

  • Both the maternal RSV vaccine and the infant RSV antibody significantly reduce the risk of severe RSV illness and hospitalization in babies.

  • Neither the maternal RSV vaccine nor the infant antibody can give you or your baby RSV, because they do not contain live viruses.

    1. Public Health Agency of Canada. Respiratory syncytial virus (RSV) vaccines: Canadian Immunization Guide [Internet]. Ottawa (ON): Public Health Agency of Canada; 2024 Aug 9 [cited 2024 Nov 5]. Available from: https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/respiratory-syncytial-virus.html

    2. Bourdeau M, Mitchell I, Grubb E, Defoy I. Pediatric RSV-associated hospitalizations before and during the COVID-19 pandemic. JAMA Netw Open. 2023;6(10). doi:10.1001/jamanetworkopen.2023.36863

    3. Mitchell I, Defoy I, Grubb E. Burden of respiratory syncytial virus hospitalizations in Canada. Can Respir J. 2017;2017:4521302.  DOI: 10.1155/2017/4521302

    4. National Advisory Committee on Immunization [NACI]. Statement on the prevention of respiratory syncytial virus (RSV) disease in infants [Internet]. Ottawa (ON): Public Health Agency of Canada; 2024 May 17 [cited 2024 Jun 5]. Available from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/national-advisory-committee-immunization-statement-prevention-respiratory-syncytial-virus-disease-infants/naci-statement-2024-05-17.pdf

    5. Baraldi, E., et al. (2022). RSV disease in infants and young children: Can we see a brighter future? Hum Vaccin Immunother, 18(4), 2079322.

    6. Rha B, Dahl RM, Moyes J, et al. Respiratory syncytial virus-associated hospitalizations among young children: 2015-2016. Pediatrics. 2020;146(1)

    7. Cohen C, Zar HJ. Deaths from RSV in young infants-the hidden community burden. Lancet Glob Health. 2022;10(2)

    8. Hause AM, Avadhanula V, Aideyan L, et al. Adverse outcomes in pregnant women hospitalized with respiratory syncytial virus infection: A case series. Clin Infect Dis. 2021;72(1):138-140.

    9. Griffin MP, Yuan Y, Takas T, et al. Single-dose nirsevimab for prevention of RSV in preterm infants. N Engl J Med. 2020;383(5):415-425.

    10. Kampmann B, Jones CE, Munoz FM, et al. Bivalent prefusion F vaccine in pregnancy to prevent RSV illness in infants. N Engl J Med. 2023;388(16):1451-1464.

    11. Simões EAF, Center KJ, Tita AT, et al. Prefusion F protein-based respiratory syncytial virus immunization in pregnancy. N Engl J Med. 2022;386(17):1615-1626.

    12. Fleming-Dutra KE, Jones JM, Roper LE, et al. Use of the Pfizer respiratory syncytial virus vaccine during pregnancy for the prevention of respiratory syncytial virus-associated lower respiratory tract disease in infants: Recommendations of the Advisory Committee on Immunization Practices - United States, 2023. MMWR Morb Mortal Wkly Rep. 2023;72(41):1115–1122.

    13. Pfizer. Respiratory syncytial virus stabilized bivalent prefusion F subunit vaccine (RSVPREF / ABRYSVO) [Briefing document from Vaccines and Related Biological Products Advisory Committee Meeting] [Internet]. Silver Spring (MD): U.S. Food and Drug Administration; 2023 May 18 [cited 2024 Nov 5]. Available from: https://www.fda.gov/media/168186/download

    14. Centers for Disease Control and Prevention. Immunizations to protect infants [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; 2023 Aug 9 [cited 2024 Nov 5]. Available from: https://www.cdc.gov/rsv/immunizations-protect-infants/index.html

    15. Centers for Disease Control and Prevention. Frequently asked questions about RSVpreF (Abrysvo) vaccine for pregnant people [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; 2023 Nov 13 [cited 2024 Nov 5]. Available from: https://www.cdc.gov/vaccines/vpd/rsv/hcp/pregnant-people-faqs.html