Language selection

Government of Canada / Gouvernement du Canada

Search

Respiratory syncytial virus (RSV) vaccines: Canadian Immunization Guide

For health professionals

Last partial content update: May 2026

This chapter was updated based on the following statements from the National Advisory Committee on Immunization (NACI):

This information is captured in the table of updates.

On this page

Please note: The Public Health Agency of Canada (PHAC) recognizes that not all people giving birth or breastfeeding will identify as women or mothers. The writing in this chapter uses a gender additive approach where the term 'woman' is used alongside gender neutral language. This is intended to demonstrate a commitment to redress the historic exclusion of trans and non-binary people, whilst avoiding the risk of marginalizing or erasing the experience of women within the health care environment. The dynamic nature of language is recognized. It is likely that language deemed to be suitable or affirming in one context may not translate across others, and over the coming years will continue to change and evolve with respect to appropriate representations. In line with best practice, it is recognized that when discussing or caring for individuals in a one-on-one capacity language and documentation should reflect the gender identity of the individual.

Epidemiology

Disease description

Infectious agent

RSV is an enveloped single-stranded RNA virus from the Paramyxoviridae family. RSV is a common cause of respiratory tract infections that recur throughout life. It is the most common cause of bronchiolitis and pneumonia among infants and young children and is responsible for more severe clinical outcomes among older adults, particularly among those with comorbidities. For additional information about the RSV virus, refer to the Pathogen Safety Data Sheet.

Reservoir

Humans are the only natural reservoir.

Transmission

RSV is transmitted by direct and indirect contact with infectious respiratory tract secretions. Transmission occurs directly when droplets generated from coughs or sneezes of an infected person come into contact with the mucous membranes of the eyes, nose, mouth, or airway of another person. Indirect transmission occurs when people touch contaminated hands, surfaces, and objects and inoculate themselves by touching their mucous membranes.

Risk factors for infants

RSV infects almost all infants by 2 years of age. In infants and young children, the younger the child, the higher the risk of hospitalization. The risk of medically attended RSV appears to be higher in infants with comorbidities compared to healthy term infants entering their first RSV season. However, the majority of infants and young children who require medical office or emergency department visits associated with RSV are born at term with no underlying comorbidities.

Prematurity is a notable risk factor for RSV hospitalization. Early preterm infants and young children (born at less than 32 weeks gestational age) have significantly higher rates of severe RSV. Also at higher risk of RSV hospitalization are young children with chronic respiratory, cardiac or immunocompromising conditions. List 1 describes medical conditions that increase an infant's risk of severe RSV disease.

List 1: Infants at increased risk of severe RSV disease

Infants at increased medical risk of severe RSV disease during their first and second RSV season:

  • Premature infants born at less than 32 weeks gestational age
  • Chronic lung disease, including bronchopulmonary dysplasia, requiring ongoing assisted ventilation, oxygen therapy or chronic medical therapy in the 6 months prior to the start of the RSV season
  • Cystic fibrosis with respiratory involvement and/or growth delay
  • Haemodynamically significant chronic cardiac disease
  • Severe immunodeficiencyFootnote 1 Footnote 2
  • Severe congenital airway anomalies impairing clearing of respiratory secretions
  • Neuromuscular disease impairing clearing of respiratory secretions
  • Down syndrome
Footnote 1

For a list of immunocompromising conditions, refer to the COVID-19 vaccines chapter

Return to footnote 1 referrer

Footnote 2

Criteria for severe immunodeficiency with HIV: CD4 less than 750 cells/µL if age less than 1 year or CD4 less than 500 if age 1 to 2 years

Return to footnote 2 referrer

There is a higher burden of RSV hospital admissions in northern and remote settings compared to the rest of Canada. High rates of RSV hospitalization, particularly among those less than 1 year of age, have been observed among infants in the Yukon, Northwest Territories, and Nunavut as well as in Nunavik, the northernmost part of Quebec.

Risk factors for adults

Risk factors for severe RSV disease include increasing age, presence of comorbidities (List 2), and intersecting structural and social determinants of health. Individuals at highest risk include adults who are residents of nursing homes and other chronic care facilities, have had a lung transplant, have had a hematopoietic stem cell transplant in the previous two years or who remain on immunosuppression, are on home oxygen or require chronic oxygen therapy regardless of living at home or elsewhere, or are receiving dialysis.

List 2: Chronic health conditions for which RSV vaccination is particularly important
  • Cardiac or pulmonary disorders (includes chronic obstructive pulmonary disease [COPD], asthma, cystic fibrosis, and conditions affecting ability to clear airway secretions)
  • Diabetes mellitus and other metabolic diseases
  • Moderate and severe immunodeficiency (refer to the list of immunocompromising conditions developed for COVID-19)
  • Chronic renal disease
  • Chronic liver disease
  • Neurologic or neurodevelopmental conditions (includes neuromuscular, neurovascular, neurodegenerative [e.g., dementia], neurodevelopmental conditions, and seizure disorders, but excludes migraines and psychiatric conditions without neurological conditions)
  • Class 3 obesity (defined as BMI of 40 kg/m2 and over).

Seasonal and temporal patterns

RSV exhibits a seasonal infection cycle that is somewhat variable by region. In temperate climates in the Northern Hemisphere, annual RSV outbreaks begin in the fall and continue to early spring. Prior to the COVID-19 pandemic, the RSV season in most of Canada was typically November to April. Information on current RSV activity in Canada can be found on the respiratory virus detections in Canada website.

Spectrum of clinical illness

Most RSV infections are respiratory tract infections that present as nasal congestion, cough, low grade fever and loss of appetite and last approximately 1 to 2 weeks. Approximately 20 to 30% of infected infants develop bronchiolitis or pneumonia. Croup or otitis media may also occur. Recurrent infections occur throughout life, with subsequent infections usually less severe than the first until older adulthood, when RSV infection can again lead to severe disease. Older children and most adults usually present with symptoms similar to the common cold. Severe pneumonia may occur in older adults, particularly among those with certain chronic medical conditions (List 2) and in immunocompromised individuals of any age.

Mortality is very low (6.9 per 1 million live births) in high income countries among children receiving supportive care. Mortality is more common among older adults hospitalized for RSV, at approximately 5 to 10% and increases with increasing age and presence of comorbidities.

Disease distribution

RSV occurs worldwide, with virtually all children infected by age two. Globally, RSV is an important cause of acute lower respiratory tract infection and a major cause of hospital admissions in young children, for whom it has been estimated that RSV is associated with about 31% of pneumonia cases and 33 million episodes of acute lower respiratory tract infections. In Canada, approximately 2% of all infants are hospitalized with RSV in their first year of life. In some remote communities, RSV hospitalization rates have been as high as 5 to 17% of all live births. RSV is not a notifiable disease in Canada, consequently the burden and risk of RSV in older adults is likely underestimated.

Preparations authorized for use in Canada

Monoclonal antibodies for infants

RSV vaccines for pregnant women and pregnant people

RSV vaccines for adults

For complete prescribing information, consult the product leaflets or information contained within Health Canada's authorized product monographs available through the Drug Product Database. Refer to Table 1 in Contents of immunizing agents authorized for use in Canada in Part 1 for a list of all vaccines authorized for use in Canada and their contents.

Immunogenicity, efficacy and effectiveness

Monoclonal antibodies

Nirsevimab and clesrovimab have been shown to reduce hospital admission associated with RSV by 83 to 84%. Nirsevimab, clesrovimab and palivizumab show efficacy in reducing the rate of medically attended RSV infections and are likely efficacious at preventing ICU admissions associated with RSV. There is limited evidence on the efficacy for prevention of death due to RSV.

The protective efficacy of monoclonal antibodies takes effect immediately. Nirsevimab and clesrovimab have a longer durability of protection compared to previous monoclonal antibodies (palivizumab) and, if administered at birth, protection is high in the first months of life when infants are most at risk for RSV and may provide full-season protection.

Infants living in some remote northern communities are at very high risk of hospitalization for RSV. Although RSV monoclonal antibodies are expected to be highly efficacious, data in this group are very limited.

RSVpreF (Abrysvo™), RSVPreF3 (Arexvy), and mRNA-1345 (mRESVIA) vaccines

RSVpreF vaccine administered to pregnant women and pregnant people results in a 57 to 82% reduction in RSV associated hospital admission in their infants. It also reduces medically attended RSV respiratory tract infection in their infants by 54 to 64% in their first RSV season. The protective efficacy of RSVpreF takes some time to develop; therefore, it is optimally administered at least 2 weeks before birth to allow for the transplacental transfer of protective antibodies. Efficacy of RSVpreF vaccine is high in the first months of life when infants are most at risk for RSV during the RSV season.

The efficacy of RSVpreF vaccine in preventing RSV infection in pregnant women and pregnant people has not yet been evaluated.

All RSV vaccines provide good protection against medically attended RSV respiratory tract infections (RTI) and severe RSV outcomes such as hospitalization for adults 60 years of age and older. While data is more limited, all RSV vaccines trigger a strong immune response in adults at increased risk of severe RSV disease. NACI will continue to monitor emerging evidence as it becomes available.

RSV vaccines have been shown to provide protection for at least 3 years, however waning of the immune response after the first dose has been observed. The importance of this is not yet clear as there is no established immune correlate of protection.

Recommendations for use

Jurisdictions should define their RSV season based on local epidemiology to determine when to provide RSV immunizing products.

Infants and children

Routine schedule for infants

RSV immunization is recommended to protect all infants against RSV in their first RSV season. Depending on the jurisdictional RSV immunization program, one of the following routine immunization approaches may be offered through publicly-funded programs:

For more information on the RSVpreF vaccine, refer to Recommendations for use in Pregnant women and pregnant people.

RSV monoclonal antibody (nirsevimab and clesrovimab) administration should begin at the start of the RSV season. Supply may be prioritized for infants born during the RSV season or for the youngest infants at the start of RSV season.

Monoclonal antibodies are not recommended for an infant who has a current confirmed RSV infection or a previous confirmed RSV infection in the current RSV season unless the infant has severe immunocompromise. Reported rates of second episodes of RSV hospitalization in the same season are very low.

If neither RSVpreF nor monoclonal antibodies (nirsevimab or clesrovimab) are available through publicly-funded immunization programs, individuals, parents or guardians may consider accessing these products through the private market in consultation with their healthcare provider. Those considering immunization outside of publicly-funded programs to protect infants should consider factors that put infants at risk for severe RSV disease; including infants aged less than 3 to 6 months at the start of the RSV season, infants born during the RSV season, and those at increased risk of severe RSV disease (refer to High risk infants and children).

High risk infants and children

RSV monoclonal antibodies (nirsevimab or clesrovimab) are recommended for infants and children at increased risk of severe RSV disease, including:

Clesrovimab is not authorized for infants and children at ongoing risk in their second RSV season but could be considered off-label based on evidence of immunogenicity and safety.

If nirsevimab or clesrovimab are not available, palivizumab should be used according to the NACI Statement on the Recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants (2022).

Additional monoclonal antibody doses

An additional dose of monoclonal antibody (nirsevimab or clesrovimab) is recommended after surgery requiring cardiopulmonary bypass and can be considered at the conclusion of extracorporeal membrane oxygenation. Refer to the product monograph in the Drug Product Database for dosing guidance.

Pregnant women and pregnant people

Depending on the jurisdictional RSV immunization program (refer to Recommendations for use in Infants and children), a single dose of the RSVpreF vaccine may be recommended to a pregnant woman or pregnant person, in advance of, or during the RSV season to prevent severe RSV disease in their infant.

Although RSVpreF is authorized for administration during pregnancy at 32 to 36 weeks of gestation, it is recommended to be administered at 28 to 36 weeks of gestation and in advance of, or during, the RSV season, to protect infants expected to be born during the RSV season as determined by local RSV epidemiology, to allow the development of a humoral immune response and passive antibody transfer. If RSVpreF is not received at least 2 weeks before birth, there would be insufficient time to allow for the transplacental transfer of protective antibodies.

RSVpreF may be administered regardless of past RSV infection.

Due to a lack of data, there is no recommendation for repeat vaccine dosing for subsequent pregnancies. To provide RSV protection to infants born in subsequent pregnancies, administration of a monoclonal antibody (nirsevimab or clesrovimab) to the infant after birth is recommended.

Adults 18 years of age and older and at high risk of severe RSV disease

High risk individuals

A single dose of RSV vaccine is recommended for adults 18 years of age and older who:

A single dose of RSV vaccine is recommended for adults 65 to 74 years of age and who are at increased risk of severe RSV disease (List 2).

A single dose of RSV vaccine may be considered by adults 18 to 64 years of age at increased risk of severe RSV disease and who are not among the recommended groups for publicly funded vaccine programs, following discussion with their health care provider.

For adults 18 years of age and older, a single dose of RSVpreF or mRNA-1345 can be used. For adults 50 years of age and older, a single dose of RSVPreF3, RSVpreF or mRNA-1345 can be used. The RSV vaccine dose is optimally administered just before the start of the RSV season.

A single dose of RSV vaccine is expected to provide protection from RSV disease for at least 3 years.

Adults 75 years of age and older

Routine schedule

To reduce morbidity and mortality associated with RSV infection in older adults, a single dose of RSV vaccine (RSVpreF, RSVPreF3 or mRNA-1354) is recommended for all adults 75 years of age and older, optimally administered just before the start of the RSV season.

Jurisdictions and communities may consider vaccinating individuals in or from First Nations, Inuit and Métis communities at a younger age given the available evidence on the increased burden of illness due to intersecting structural and social determinants of health.

The need for a subsequent RSVpreF, RSVPreF3, or mRNA-1345 vaccine dose for adults and an optimal strategy for boosting these vaccine responses are not yet clear. NACI will continue to monitor emerging evidence as it becomes available.

Vaccination of specific populations

Infants born prematurely

To prevent severe RSV disease during their first RSV season, RSV monoclonal antibodies (nirsevimab or clesrovimab) are recommended for infants born prematurely. Infants and children born at less than 32 weeks gestational age should be routinely offered monoclonal antibodies for their second RSV season. Clesrovimab is not authorized for infants and children at ongoing risk in their second RSV season but could be considered off-label based on evidence of immunogenicity and safety.

If nirsevimab or clesrovimab are not available, palivizumab should be used according to the NACI Statement on the Recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants (2022), for infants born at less than 33 weeks gestational age.
Refer to Immunization of infants born prematurely in Part 3 for additional information about vaccination of premature infants.

Infants and children whose transportation for severe RSV disease treatment is complex

RSV monoclonal antibodies (nirsevimab or clesrovimab) should be provided to infants entering, or born during, their first RSV season whose transportation for severe RSV disease treatment is complex.

Infants and children whose risk of severe RSV disease intersects with established social and structural health determinants

RSV monoclonal antibodies (nirsevimab or clesrovimab) should be provided to infants entering, or born during, their first RSV season whose risk of severe RSV disease intersects with established social and structural health determinants which due to social, environmental, and economic factors, rooted in the history of colonization and systemic racism (i.e., structural inequity) are experienced by some Indigenous communities across First Nations, Métis and Inuit populations. This applies to infants who live in or are part of First Nations, Métis, and Inuit communities.

If nirsevimab or clesrovimab are not available, palivizumab should be used according to the NACI Statement on the Recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants (2022).

Breastfeeding women and people

There is no evidence, but it is possible, based on other vaccines studies, that there would be a modest transfer of protective antibodies through breast milk if the breastfeeding woman or breastfeeding individual received vaccine in pregnancy or during breast feeding.

Persons with chronic medical conditions

Infants and children

Chronic lung disease

To prevent severe RSV disease during their first and second RSV seasons, RSV monoclonal antibodies (nirsevimab or clesrovimab) are recommended for infants and children with chronic lung disease (List 1). Nirsevimab or clesrovimab should be provided for infants and children with chronic lung disease (including bronchopulmonary dysplasia) requiring ongoing assisted ventilation, oxygen therapy or chronic medical therapy in the 6 months prior to the start of the RSV season, as well as infants and children with cystic fibrosis with respiratory involvement and/or growth delay.

Clesrovimab is not authorized for infants and children at ongoing risk in their second RSV season but could be considered off-label based on evidence of immunogenicity and safety.

If nirsevimab or clesrovimab are not available, palivizumab should be used according to the NACI Statement on the Recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants (2022).

Refer to Immunization of persons with chronic diseases in Part 3 for additional information about vaccination of people with chronic diseases.

Heart disease

To prevent severe RSV disease during their first and second RSV seasons, RSV monoclonal antibodies (nirsevimab or clesrovimab) are recommended for infants and children with haemodynamically significant chronic cardiac disease.

Clesrovimab is not authorized for infants and children at ongoing risk in their second RSV season but could be considered off-label based on evidence of immunogenicity and safety.

If nirsevimab or clesrovimab are not available, palivizumab should be used according to the NACI Statement on the Recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants (2022).

Down syndrome

To prevent severe RSV disease during their first and second RSV seasons, RSV monoclonal antibodies (nirsevimab or clesrovimab) are recommended for infants with Down syndrome.

Clesrovimab is not authorized for infants and children at ongoing risk in their second RSV season but could be considered off-label based on evidence of immunogenicity and safety.

If nirsevimab or clesrovimab are not available, palivizumab should be used according to the NACI Statement on the Recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants (2022).

Refer to Immunization of persons with chronic diseases in Part 3 for additional information about vaccination of people with chronic diseases.

Adults

Persons with some chronic diseases are at higher risk of serious outcomes associated with RSV. The increased risk of severe RSV disease is likely variable depending on the severity of the chronic medical condition with individuals at more severe stages of the disease expected to be at highest risk. Each person who has chronic medical condition(s) is different and presents unique factors to consider regarding immunization such as age, presence of one or multiple risk factors, increased risk of exposure to RSV disease or structural and social determinants like limited access to care.

Refer to List 2: Chronic health conditions for which RSV vaccination is particularly important and Recommendations for use.

Refer to Immunization of persons with chronic diseases in Part 3 for additional information.

Persons who are immunocompromised

Infants and children

In general, people who are immunocompromised (refer to COVID-19 vaccines in Part 4 for a list of immunocompromising conditions) are more susceptible to vaccine-preventable infections and may have more severe infections. Monoclonal antibodies (nirsevimab or clesrovimab) are recommended to prevent severe RSV disease during the first and second RSV seasons in infants and children who have severe immunodeficiency. Infants who are severely immunocompromised may receive a monoclonal antibody (nirsevimab or clesrovimab) even after RSV infection, as they may not develop an immune response to RSV infection.

There are efficacy and safety data to support the use of the RSV monoclonal antibody nirsevimab in infants and children with immunocompromise, and clesrovimab is authorized in infants less than 12 months of age, including those who are immunocompromised. The efficacy and safety of clesrovimab is currently being evaluated in clinical trials in immunocompromised infants and children less than 24 months of age.

Clesrovimab is not authorized for infants and children at ongoing risk in their second RSV season but could be considered off-label based on evidence of immunogenicity and safety.

If nirsevimab or clesrovimab are not available, palivizumab should be used according to the NACI Statement on the Recommended use of palivizumab to reduce complications of respiratory syncytial virus infection in infants (2022).

Refer to Immunization of immunocompromised persons in Part 3 for additional general information about vaccination of people who are immunocompromised.

Adults

Persons with immunocompromising conditions are at higher risk of serious outcomes associated with RSV. The increased risk of severe RSV disease is likely variable depending on the severity of the immunocompromise at more severe stages of disease expected to be at highest risk. Each person who is immunocompromised is different and presents unique factors to consider regarding immunization such as age, presence of one or multiple risk factors, increased risk of exposure to RSV disease or structural and social determinants like limited access to care.

Being immunocompromised is not a precaution to immunization with RSVpreF. However, there are no data on its use in pregnant women and pregnant people with immunocompromise. They may have a diminished immune response to the vaccine.

Refer to List 2: Chronic health conditions for which RSV vaccination is particularly important and Recommendations for use.

Refer to Immunization of immunocompromised persons in Part 3 for additional information.

Adults in healthcare institutions

Residents of nursing homes and other chronic care facilities have a higher likelihood of severe clinical outcomes of RSV disease compared to those with other living situations. Refer to Recommendations for use in Adults 18 years of age and older and at high risk of severe RSV disease.

Refer to Immunization of patients in health care institutions in Part 3 for additional information.

Administration practices

Dose and route of administration

Dose for infants

For infants entering their first RSV season, nirsevimab is administered as a single dose of 50 mg/0.5 mL for infants weighing less than 5 kg, and a single dose of 100mg/1 mL for infants weighing 5 kg or more. For most children entering their second RSV season who are at ongoing risk of severe RSV disease, nirsevimab 200 mg (2 x 100 mg/1 mL) is given in 2 different injection sites. However, if the child weighs less than 10 kg entering their second RSV season, consideration can be given to administering a single dose of 100 mg at clinical discretion.

For infants entering their first season, clesrovimab is administered as a single dose of 105 mg/0.7 mL regardless of weight. For children entering their second RSV season who are at ongoing risk of severe RSV disease, consideration can be given to administering clesrovimab 210 mg (2 x 105 mg/0.7 mL) as per the clinical trial at clinical discretion.

Palivizumab is given at a dose of 15 mg/kg of body weight, approximately every 28 days, during RSV season, for a total of 4 or 5 doses.

Dose for pregnant women and pregnant persons

RSVpreF (Abrysvo™) vaccine is administered as a single 0.5 mL dose in pregnancy. Although it is authorized for use between 32 and 36 weeks of gestation, it is recommended to be administered from 28 to 36 weeks of gestation.

Dose for adults

For adults 18 years of age and older, RSVpreF (Abrysvo™) or mRNA-1345 (mRESVIA) is administered as a single 0.5 mL dose.

For adults 50 years of age and older, RSVPreF3 (Arexvy) is administered as a single 0.5 mL dose.

Route of administration

Monoclonal antibodies are administered by intramuscular (IM) injection to infants and children.

RSVpreF (Abrysvo™) vaccine is administered IM to pregnant women and pregnant people. RSV vaccines (RSVpreF, RSVPreF3, and mRNA-1345) are administered IM in adults.

Refer to Vaccine administration practices in Part 1 for additional information about pre-vaccination and post-vaccination counselling, vaccine preparation and administration technique and infection prevention and control.

Concurrent administration with other vaccines

Nirsevimab, clesrovimab and palivizumab are passive immunizing agents directed specifically against RSV. These monoclonal antibodies do not interfere with the immune response to other vaccines. Nirsevimab, clesrovimab or palivizumab can be administered at the same time as, or at any time before or after, other immunization products.

RSV vaccines for adults can be administered at the same time as, or at any time before or after, other vaccines. However, if possible, RSV vaccines for adults should be given at least 6 weeks before or after non-seasonal vaccines, for example, shingles or diphtheria-tetanus vaccines, to avoid inadvertently attributing an adverse event from another vaccine to the RSV vaccine.

Refer to Blood products, human immunoglobulin and timing of immunization and Timing of vaccine administration in Part 1 for additional information.

Storage requirements

RSV monoclonal antibodies should be stored between 2°C and 8°C in their original containers and must not be frozen.

RSVpreF (Abrysvo™) and RSVPreF3 (Arexvy) should be stored in a refrigerator between 2°C and 8°C in their original containers to protect them from light. Neither vaccine can be frozen.

mRNA-1345 (mRESVIA) should be stored frozen between -40°C and -15°C for up to 18 months. Once thawed, the vaccine should not be refrozen. Within the 18-month shelf-life, the unopened vaccine may be stored refrigerated between 2°C and 8°C, protected from light, for a maximum of 90 days. Unopened pre-filled syringes may be stored at 8°C to 25°C for a total of 24 hours after removal from refrigerator conditions.

For additional information, consult the product monographs available through Health Canada's Drug Product Database. Refer to Storage and handling of immunizing agents in Part 1 for additional information.

Safety and adverse events

Common and very common adverse events

Common adverse events occur in 1% to less than 10% of vaccinees. Very common adverse events occur in 10% or more of vaccinees. Adverse events following administration of RSV monoclonal antibodies are uncommon.

In randomized controlled trials the rates of local and systemic adverse events were similar for those receiving either nirsevimab or palivizumab as for those receiving a placebo. In healthy full-term infants, the rates of local and systemic adverse events for those receiving clesrovimab were similar to those receiving placebo, and among infants at increased risk of severe RSV disease, the rate of systemic adverse events for those receiving clesrovimab was similar to those receiving palivizumab.

The most-reported adverse events following immunization with RSVpreF vaccine in pregnant women and pregnant individuals were pain at the injection site, headache and myalgia.

Overall, RSVpreF, RSVPreF3 and mRNA-1345 are well-tolerated. The most common adverse events after RSV vaccination in older adults are usually mild or moderate and include pain at the injection site, fatigue, headache, and muscle or joint pain.

Uncommon, rare and very rare adverse events

Uncommon adverse events occur in 0.1% to less than 1% of vaccinees. Rare and very rare adverse events occur, respectively, in 0.01% to less than 0.1% and less than 0.01% of vaccinees. In infants, fever and/or rash at the injection site occurred at a rate of 0.5% within 7 days following administration of RSV monoclonal antibodies. Compared with placebo, nirsevimab and clesrovimab do not increase the risk of severe systemic adverse events in infants.

RSVpreF vaccine does not increase the risk of severe systemic adverse events in pregnant women and pregnant people or their infants.

Serious adverse events following administration of palivizumab, mostly hypersensitivity reactions, are rare at 1.3 to 3.4 per 10,000 doses administered. Anaphylaxis occurs in approximately 1 per 1 million doses, similar to the rate seen with immunization in general.

Other safety issues

Repeated injections of a humanized monoclonal antibody have raised concern for the development of immune mediated disease. However, studies have not shown an increased risk of autoimmune disease or atopy in children exposed to palivizumab.

Some studies found an increase in preterm births among RSVpreF vaccine recipients compared to placebo recipients. This was not observed in high-income countries like Canada. Since then, real-world evidence has emerged that does not find a relationship between RSVpreF use and preterm birth.

RSV vaccines have a good safety profile in adults. An increased risk of Guillain-Barré syndrome (GBS) after vaccination with either RSVpreF or RSVPreF3 has been identified in adults 65 years of age and older, however, RSV infection may also increase the risk of GBS in this age group. Information currently available is insufficient to determine if there is an increased frequency of these events associated with the vaccines in adults less than 65 years of age. NACI will continue to carefully monitor the evidence on the safety of RSVpreF, RSVPreF3, and mRNA-1345 vaccines in adults and will update guidance accordingly.

Appropriate vaccine administration is essential to the optimal safety and efficacy of vaccines. To avoid administration errors where RSV vaccines are inadvertently administered to the wrong populations, for example, children being given the RSVpreF vaccine, refer to Vaccine administration practices chapter, Table 2: Vaccine provider administration check list.

Guidance on reporting adverse reactions following RSV monoclonal antibody administration and adverse events following immunization (AEFI)

To ensure the ongoing safety monitoring in Canada of passive immunizing agents such as nirsevimab, clesrovimab, and palivizumab, and the active immunizing agents, RSVpreF, RSVPreF3, and mRNA-1345, reporting of adverse reactions and events by health care providers is critical. In some jurisdictions, reporting is mandatory under the law.

Vaccine providers are asked to report AEFIs through local public health officials and to check for specific AEFI reporting requirements in their province or territory. In general, any serious or unexpected adverse event believed to be temporally related to vaccination should be reported.

When a serious or unexpected adverse reaction follows the administration of a passive immunizing agent such as nirsevimab, clesrovimab or palivizumab, report the adverse drug reaction to the Canada Vigilance Program using the Side Effect Reporting Form available on the program web page. The Canada Vigilance Program collects and assesses reports of suspected adverse reactions to health products, including biologics. If palivizumab or nirsevimab was given along with an active immunizing agent, the adverse event(s) should also be reported through local public health officials.

Refer to Vaccine Safety and Pharmacovigilance and Adverse Events Following Immunization in Part 2 for additional information on vaccine safety. Refer to Contents of immunizing agents authorized for use in Canada in Part 1 for additional information on the components of nirsevimab, clesrovimab, palivizumab and RSVpreF vaccine.

Contraindications and precautions

Nirsevimab, clesrovimab, palivizumab, RSVpreF, RSVPreF3 and mRNA-1345 are contraindicated in individuals with a known hypersensitivity or history of a severe allergic reaction (e.g., anaphylaxis) to any component of the products. A known hypersensitivity to other humanized monoclonal antibodies is also a contraindication for nirsevimab, clesrovimab and palivizumab. Refer to Contraindications and precautions chapter for more information on allergies and to Contents of immunizing agents authorized for use in Canada for a list of all vaccines authorized for use in Canada and their contents.

Minor illnesses such as the common cold, with or without fever, are not contraindications to use of RSV monoclonal antibodies or RSV vaccines. Moderate to severe illness, with or without fever, is a reason to consider deferring administration. The decision to delay administration of an immunizing agent will depend on the severity and etiology of the underlying disease as well as the risk of not immunizing.

Chapter revision process

This chapter was revised based on the National Advisory Committee on Immunization's (NACI) Updated Guidance on Respiratory Syncytial Virus (RSV) Vaccines for Older Adults and for Adults at High Risk of Severe RSV Disease (PDF) and Updated guidance to protect infants and children from respiratory syncytial virus (RSV) disease: use of monoclonal antibodies (nirsevimab and clesrovimab) and the RSVpreF vaccine (PDF).

Acknowledgments

This chapter revision has been prepared by E Abrams, N Mohamed and A Nunn on behalf of the NACI RSV Working Group. The chapter was reviewed by A Killikelly, W Siu, J Zafack, M Tunis and N Brousseau.

The CIG gratefully acknowledges the contribution of: N Haddad and C. Tremblay.

Selected references

Footnotes

Footnote 1

Autonomous decisions should be made by Indigenous Peoples with the support of healthcare and public health partners in accordance with the United Nations Declaration on the Rights of Indigenous Peoples Act.

Return to footnote 1 referrer

Page details

2026-05-11