Respiratory syncytial virus (RSV) vaccines: Canadian Immunization Guide
For health professionals
Last partial content update: August 2024
This chapter was updated based on the following guidance from the National Advisory Committee on Immunization (NACI):
- August 9, 2024: Statement on the prevention of respiratory syncytial virus (RSV) disease in older adults
On this page
- Key information
- Epidemiology
- Preparations authorized for use in Canada
- Immunogenicity, efficacy and effectiveness
- Recommendations for use
- Vaccination of specific populations
- Infants born prematurely
- Infants and children with chronic diseases
- Infants and children who are immunocompromised
- Infants and children 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
- Pregnant or breastfeeding women and pregnant or breastfeeding people
- Older adults
- Administration practices
- Storage requirements
- Safety and adverse events
- Chapter revision process
- Acknowledgments
- Selected references
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.
Key information
What
- Respiratory syncytial virus (RSV) infection is a major cause of lower respiratory tract illness, particularly among infants, young children and older adults.
- In Canada, RSV causes yearly outbreaks of respiratory tract disease, usually starting in late fall and running through to early spring.
- Reinfections with RSV are common but illness is usually milder with subsequent infections until older adulthood, when RSV can again lead to severe disease.
- Immunization products to protect infants against RSV include: two monoclonal antibody preparations, nirsevimab and palivizumab which are administered directly to infants, as well as the RSVpreF vaccine (AbrysvoTM), which is administered during pregnancy to protect the infant through the passive transfer of maternal antibodies.
- Two vaccines are available to protect adults 60 years of age and older from RSV; RSVPreF3 (Arexvy) and RSVpreF (AbrysvoTM).
Who
- RSV immunization should be considered for any infant entering, or born during, their first RSV season and for infants at ongoing increased risk during their second RSV season.
- Nirsevimab, the RSV monoclonal antibody, is preferred over palivizumab and the RSVpreF (AbrysvoTM) vaccine.
- Nirsevimab should be prioritized for infants:
- With certain medical conditions that place them at increased risk of severe RSV disease including prematurity (List 1)
- With certain medical conditions (List 1) who are at ongoing increased risk for severe RSV disease during their second RSV season
- Whose transportation for severe RSV disease treatment is complex, and/or who live in or are part of First Nations, Métis, and Inuit communities where risk of severe RSV disease intersects with established social and structural health determinants.
- If nirsevimab is not available, palivizumab may be used for certain infants at very high risk for severe RSV disease. For more information refer to sections: Infants born prematurely, Infants and children with chronic diseases, Infants and children whose transportation for severe RSV disease treatment is complex, and Infants and children whose risk of severe RSV disease intersects with established social and structural health determinants.
- The RSVpreF (AbrysvoTM) vaccine may be considered by a pregnant woman or pregnant person, together with their care provider, in advance of, or during, the RSV season, to prevent RSV disease in their infant. There is no expected additional benefit to using both RSVpreF (AbrysvoTM) and nirsevimab for healthy infants. However, if RSVpreF (AbrysvoTM) was received during pregnancy and the infant is at increased risk for severe RSV disease or is born less than 2 weeks after RSVpreF (AbrysvoTM) was given, nirsevimab should still be provided.
- RSV immunization is recommended for adults:
- 75 years of age and older, particularly for those who are at increased risk of severe RSV disease (List 2)
- 60 years of age and older who are residents of nursing homes and other chronic care facilities.
- RSV immunization may be considered as an individual decision for adults 60 to 74 years of age in consultation with their health care provider
How
- RSV immunizing products are optimally administered just before the start of the RSV season. Jurisdictions should define their RSV season based on local epidemiology to determine when to provide RSV immunizing products.
- The schedule and dosing of nirsevimab and palivizumab given to infants entering or born during the RSV season are as follows:
- A single dose of nirsevimab is administered to infants. Those weighing less than 5 kg should receive a 0.5 mL dose (50 mg/0.5 mL) and those weighing 5 kg or more should receive a 1 mL dose (100 mg/1 mL).
- For a second RSV season, nirsevimab is given as a single dose of 200 mg (2 x 100 mg/1 mL). However, if the child weighs less than 10 kg, a single dose of 100 mg may be considered at clinical discretion.
- For palivizumab, a series of 4 or 5 doses, each of 15 mg/kg of body weight, are administered approximately 28 days apart throughout the RSV season.
- A second dose of palivizumab should follow at 21 to 28 days and the interval between subsequent doses is 28 to 35 days.
- An additional dose should be given after cardiac bypass or extracorporeal membrane oxygenation.
- An additional dose may be considered in remote northern areas where RSV outbreaks may continue longer than is usual elsewhere.
- A 0.5 mL dose of RSVpreF (AbrysvoTM) vaccine is administered during pregnancy between 32 and 36 weeks gestation.
- The protective efficacy of RSVpreF (AbrysvoTM) 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.
- A single 0.5 mL dose of RSVPreF3 (Arexvy) or RSVpreF (AbrysvoTM) is administered intramuscularly in adults 60 years of age and older.
Why
- RSV is the most common cause of bronchiolitis and pneumonia among infants and young children.
- RSV disease can have serious complications for infants, including hospitalization and intensive care unit admission, as well as significant impact on their caregivers and families.
- RSV accounts for a significant burden of disease in older adults, particularly those with certain chronic health conditions (List 2), and can result in serious complications, including hospitalization, intensive care unit (ICU) admission and death.
- Immunization of older adults with RSV vaccine can reduce medically attended RSV respiratory tract infections and hospitalizations due to RSV.
- The RSV monoclonal antibodies, nirsevimab and palivizumab, along with the RSVpreF (AbrysvoTM) vaccine can help protect infants from RSV disease by giving the infant antibodies, either via direct injection or transplacental transfer.
- Reducing severe outcomes from RSV in infants and older adults at the population level may help to protect health system capacity.
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
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. Indeed, infants born at less than 30 weeks gestational age (wGA) have RSV hospitalization rates of 7.7 to 13.6% in the first year of life. 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 risk of severe RSV disease during their first RSV season:
- All premature infants (i.e., born at less than 37 wGA)
- 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 1Footnote 2
- Severe congenital airway anomalies impairing clearing of respiratory secretions
- Neuromuscular disease impairing clearing of respiratory secretions
- Down syndrome
- All those listed above, except for infants born at less than 37 wGA and infants with Down syndrome who do not have another medical condition on the list.
- 1
-
For a list of immunocompromising conditions, refer to the COVID-19 vaccines chapter
- 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
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.
Adults 75 years of age and older, particularly those with certain chronic health conditions (List 2) are at increased risk of severe RSV disease, hospitalization, intensive care unit (ICU) admission and death. Serious outcomes of RSV infection are also seen in adults 60 years of age and older who are residents of nursing homes and other chronic care facilities. In addition, adults may be at increased risk of severe RSV disease due to factors that intersect with social determinants of health.
List 2: Chronic health conditions in older adults that lead to increased risk for severe RSV disease
- 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
- SYNAGIS® (palivizumab) is a passive immunizing agent (humanized monoclonal antibody). AstraZeneca Canada Inc.
- BEYFORTUSTM (nirsevimab) is a passive immunizing agent (human monoclonal antibody). Sanofi Pasteur Ltd.
RSV vaccines
- AREXVY (RSVPreF3) RSV subunit adjuvanted vaccine, GlaxoSmithKline Inc.
- ABRYSVOTM (RSVpreF) RSV subunit vaccine, Pfizer Canada.
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 has been shown to reduce hospital admission associated with RSV by 81 to 83%. It also has shown an 80% reduction in medically attended RSV respiratory tract infection in healthy infants. Both nirsevimab and palivizumab show efficacy in reducing the rate of medically attended RSV infections in infants at increased risk for severe RSV due to prematurity, congenital heart disease, and chronic lung disease, in their first and second RSV seasons.
The protective efficacy of monoclonal antibodies takes effect immediately. Nirsevimab has a longer durability of protection and, if administered at birth, protection is high in the first months of life when infants are most at risk for RSV. Nirsevimab is efficacious through 5 months of age and may provide full-season protection. Palivizumab has a shorter durability of protection compared to nirsevimab. Among all infants at risk of severe RSV infection, palivizumab prophylaxis is associated with risk reductions of approximately 38 to 86% for RSV-associated hospital admissions. In infants born at 32 wGA or earlier palivizumab was shown to reduce the risk of all-cause mortality.
Infants living in some remote northern communities are at very high risk of hospitalization for RSV. Data on effectiveness of RSV monoclonal antibodies to prevent hospitalization in this group are very limited.
RSVpreF (AbrysvoTM) and RSVPreF3 (Arexvy) vaccines
RSVpreF vaccine administered to pregnant women and pregnant people results in a reduction in RSV associated hospital admission in their infants by 57%. It also reduces medically attended RSV respiratory tract infection in their infants by 51% 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. Due to waning of the passively transferred antibodies in neonates over time, the protective effect may not exceed 6 months of age in infants.
The efficacy of RSVpreF vaccine in preventing RSV infection in pregnant women and pregnant people has not been evaluated.
Data are limited, however RSVpreF and RSVPreF3 appear to result in similar reductions in laboratory confirmed RSV respiratory tract infections (RTI) associated hospitalizations and medically attended RSV RTI for adults 60 years of age and older. The efficacy of these vaccines beyond season 1 is not yet clear. However, early data suggest that through two RSV seasons, efficacy against RSV disease may be maintained. NACI will continue to monitor emerging evidence as it becomes available.
The immune response to RSV vaccines wanes after the first dose. The importance of this is not yet clear as there is no established immune correlate of protection.
Recommendations for use
Routine schedule
If available, a dose of the RSV monoclonal antibody nirsevimab is recommended for all infants entering, or born during, their first RSV season. Supply may be prioritized for infants and children at increased risk.
For adults 60 years of age and older, one dose of either RSVpreF or RSVPreF3 is optimally administered just before the start of the RSV season.
Infants and children at increased risk
RSV monoclonal antibodies, are recommended for infants and children at increased risk of severe RSV disease (List 1). Nirsevimab is preferred over palivizumab.
A dose of nirsevimab should be prioritized for infants and children:
- Entering, or born during, their first RSV season who are at increased risk of severe RSV disease, including those who are born at less than 37 wGA (List 1)
- Entering their second RSV season and at ongoing increased risk of severe RSV disease (List 1)
- For infants entering, or born during, their first RSV season whose transportation for severe RSV disease treatment is complex, and/or whose risk of severe RSV disease intersects with established social and structural health determinants such as those experienced by some Indigenous communities across First Nations, Métis and Inuit populationsFootnote 1.
If nirsevimab is 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).
Palivizumab is given as 4 or 5 doses in a season. The interval between the first and second doses is 21 to 28 days, and the interval between subsequent doses is 28 to 35 days. The first dose of palivizumab is given at the onset of the RSV season, as determined by local epidemiology.
Infants born during the RSV season and who qualify for palivizumab prophylaxis should receive their first dose 48 to 72 hours before discharge home if possible, or promptly after discharge. Administering the first dose before discharge avoids the need to visit a health care facility soon after discharge and may improve adherence.
An infant who has already begun palivizumab prophylaxis earlier in the season and is re-hospitalized on a date when a dose is due should receive that dose as scheduled while in hospital, providing the admitting institution is able to supply palivizumab when due. Keeping to the child's existing schedule avoids the need to reschedule appointments and may improve adherence.
Monoclonal antibodies (nirsevimab and palivizumab) are not recommended for an infant who has a current confirmed RSV infection or a previous confirmed RSV infection in the current RSV season. Reported rates of second episodes of RSV hospitalization in the same season are very low. Consideration may be given in the case of severely immunocompromised infants who may still benefit from the monoclonal antibodies as they may not mount an immune response to the RSV infection.
Infants whose gestational parent received RSVpreF vaccine do not need nirsevimab unless the infant meets the medical criteria for increased risk of severe RSV disease (List 1) or the infant is born less than 2 weeks after administration of RSVpreF.
Pregnant women and pregnant people
For the prevention of severe RSV disease in infants, nirsevimab administered to the infant is recommended over RSVpreF vaccine administered to the pregnant woman or pregnant person due to current evidence of nirsevimab's superior efficacy, duration of protection, and available safety data.
The RSVpreF vaccine may be considered by a pregnant woman or pregnant person together with their care provider, in advance of, or during the RSV season to prevent severe RSV disease in their infant. Use of RSVpreF vaccine is not required if it is anticipated that nirsevimab will be administered to the infant.
RSVpreF vaccine administration should occur between 32 and 36 weeks 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.
Additional doses
An additional dose of monoclonal antibody is recommended after surgery requiring cardiopulmonary bypass and can be considered at the conclusion of extracorporeal membrane oxygenation. Refer to the product monograph for dosing guidance.
The need for a subsequent RSVpreF and RSVPreF3 vaccine dose for adults 60 years of age and older 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 are recommended for infants born prematurely. Nirsevimab is preferred over palivizumab and should be provided to infants born at less than 37 wGA and entering, or born during, their first RSV season. Infants and children born at less than 37 wGA who do not have another medical condition (List 1) and are entering their second RSV season are not thought to be at increased risk of severe RSV disease; therefore, they should not be routinely offered monoclonal antibodies for their second RSV season.
If nirsevimab is 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 gestation.
Palivizumab may be considered for infants born at 30 to less than 33 weeks gestation and aged less than 3 months at the onset of or during the RSV season if they are at high risk of exposure to RSV from day care attendance or presence of another preschool child or children in the home.
Palivizumab is not recommended for healthy premature infants born at or after 33 weeks gestation or for infants or siblings of multiple births who do not otherwise have an indication for prophylaxis.
Refer to Immunization of infants born prematurely in Part 3 for additional information about vaccination of premature infants.
Infants and children with chronic diseases
Chronic lung disease
To prevent severe RSV disease during their first and second RSV seasons, RSV monoclonal antibodies are recommended for infants and children with chronic lung disease (List 1). Nirsevimab is preferred over palivizumab and 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.
If nirsevimab is 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) as follows: Palivizumab is recommended for all infants with chronic lung disease of prematurity (infants born at less than or equal to 32 weeks gestational age and with need for supplemental oxygen (O2) greater than 21% for at least the first 28 days after birth) who are less than 24 months of age at the onset of the RSV season and have required ongoing supplemental O2 therapy or assisted ventilation in the 6 months prior to the onset of or during the RSV season.
Palivizumab may be considered for infants less than 24 months of age with severe chronic lung disease of other etiology (e.g., congenital cystic lung disease, chronic interstitial lung disease, congenital lung malformations, congenital airway abnormalities or neuromuscular conditions affecting ability to clear airway secretions) or who require home respiratory support (e.g., supplemental O2, mechanical ventilation, continuous positive airway pressure, tracheostomy) if requiring ongoing supplemental O2 or assisted ventilation in the 6 months prior to the onset of or during the RSV season.
Palivizumab is not routinely recommended for children less than 24 months of age with cystic fibrosis; however, palivizumab may be considered for those less than 24 months of age with cystic fibrosis who have severe chronic lung disease as defined by the need for ongoing supplemental O2 in the 6 months prior to the onset of or during the RSV season.
Palivizumab is not recommended for the prevention of recurrent wheezing or asthma in the absence of other indications.
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 are recommended for infants and children with haemodynamically significant chronic cardiac disease. Nirsevimab is preferred over palivizumab. If nirsevimab is 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 children with heart disease. Reimmunization is indicated for individuals undergoing cardiac surgery with cardiopulmonary bypass as soon as the individual is stable after surgery. Reimmunization can also be considered at the conclusion of extracorporeal membrane oxygenation.
Down syndrome
To prevent severe RSV disease during their first RSV season, RSV monoclonal antibodies are recommended for infants with Down syndrome. Nirsevimab is preferred over palivizumab. Infants and children with Down syndrome who do not have another medical condition (List 1) and are entering their second RSV season are not thought to be at increased risk of severe RSV disease; therefore, they should not be routinely offered monoclonal antibodies for their second RSV season.
If nirsevimab is 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) as follows: Palivizumab should be offered to children with Down syndrome who qualify for prophylaxis because of haemodynamically significant congenital heart disease, chronic lung disease, prematurity or immunodeficiency, but should not be routinely offered to all children less than 24 months of age with Down syndrome.
Refer to Immunization of persons with chronic diseases in Part 3 for additional information about vaccination of people with chronic diseases.
Infants and children who are immunocompromised
In general, people who are immunocompromised are more susceptible to vaccine-preventable infections and may have more severe infections. Monoclonal antibodies are recommended to prevent severe RSV disease during the first and second RSV seasons in infants and children who have severe immunodeficiency. Nirsevimab is preferred over palivizumab. If nirsevimab is 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).
There are efficacy and safety data to support the use of the RSV monoclonal antibody nirsevimab in infants and children with immunocompromise.
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 Immunization of immunocompromised persons in Part 3 for additional general information about vaccination of people who are immunocompromised.
Infants and children whose transportation for severe RSV disease treatment is complex
RSV monoclonal antibodies should be provided to infants and children whose transportation for severe RSV disease treatment is complex. Nirsevimab is preferred over palivizumab. Nirsevimab should be prioritized for 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
Nirsevimab should be prioritized for 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. Nirsevimab is preferred over palivizumab.
If nirsevimab is 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) as follows: Palivizumab should be offered to infants less than 36 wGA and less than 6 months of age living in remote northern Inuit communities who would require air transport for hospitalization. Palivizumab is not routinely recommended for healthy full term infants living in remote northern Inuit communities. Palivizumab may be considered for these infants if aged less than 6 months and living in a community with a very high RSV hospitalization rate, taking into consideration the burden of illness in the community and need for air transport if hospitalization or specialized ambulatory care is required.
Palivizumab may be considered for infants less than 36 wGA and less than 6 months of age living in other remote communities with documented high rates of hospitalization for RSV who would require air transport for hospitalization.
Pregnant or breastfeeding women and pregnant or breastfeeding people
To prevent severe RSV disease in their infant, a pregnant woman or pregnant person, in conversation with their pregnancy care provider, might consider immunization with RSVpreF vaccine in advance of, or during, the RSV season.
RSVpreF vaccine should be given at 32 through 36 weeks gestation to allow time for the development of an immune response and passive antibody transfer to the fetus before birth. RSVpreF needs to be administered at least 2 weeks before birth to allow for the transplacental transfer of protective antibodies.
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.
Older adults
To reduce morbidity and mortality associated with RSV infection in older adults, a single dose of RSV vaccine, either RSVPreF3 or RSVpreF, is recommended for adults 75 years of age and older, particularly older adults at increased risk of severe RSV disease (see List 2).
Adults 60 years of age and older who are residents of nursing homes and other chronic care facilities are among those at highest risk for severe outcomes from RSV disease. They should be vaccinated with either RSVPreF3 or RSVpreF vaccine.
Adults 60 to 74 years of age, and not among the recommended groups for publicly funded RSV vaccine programs, may consider RSV immunization in consultation with their healthcare provider. The duration of protection of the RSV vaccine is not yet known, and it is unclear if the protection offered by vaccination can be boosted by subsequent doses. Therefore, healthy individuals who are less than 75 years of age may want to discuss deferring vaccination with their health care providers to a future time when they may be at greater risk of severe RSV disease and the vaccine may confer greater benefit.
Adults who live in or are part of some First Nations, Métis, and Inuit communities might consider RSV vaccination at a younger age given the evidence for an increased burden of illness due to social, environmental, and economic factors, rooted in the history of colonization and systemic racism (i.e., structural inequity).
Administration practices
Dose and route of administration
Dose
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.
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.
RSVpreF (AbrysvoTM) vaccine is administered as a single 0.5 mL dose in pregnancy between 32 and 36 weeks gestation.
For adults 60 years of age and older, RSVPreF3 (Arexvy) or RSVpreF (AbrysvoTM) 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 (AbrysvoTM) vaccine is administered IM to pregnant women and pregnant people. RSV vaccines 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 and palivizumab are passive immunizing agents directed specifically against RSV. These monoclonal antibodies do not interfere with the immune response to other vaccines. Nirsevimab or palivizumab can be administered at the same time as, or at any time before or after, other immunization products.
RSV vaccines can be administered at the same time as, or at any time before or after, other vaccines. However, if possible, RSV vaccine 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.
Some studies suggest that concurrent administration of the RSV and influenza vaccines may result in a lower immune response, but the clinical significance of this is unknown.
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.
RSV vaccines should be stored in a refrigerator between 2°C and 8°C in their original containers to protect them from light. RSV vaccines must not be frozen.
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.
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 and RSVPreF3 are well-tolerated in adults 60 years of age and older. 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 does not increase the risk of severe systemic adverse events in infants and 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 have found an increase in preterm births among RSVpreF vaccine recipients compared to placebo recipients. This was not observed in high-income countries like Canada. It is unclear whether there is a causal relationship with the vaccine; the currently available data are inconclusive. By limiting vaccine administration to 32 through 36 weeks gestation, the potential risk of preterm birth is reduced. NACI will continue to monitor the RSVpreF vaccine safety data and will update its recommendation if needed.
Safety data are limited among adults 60 years of age and older. However, early safety data suggest a potential increased rate of atrial fibrillation events and inflammatory neurologic events, including Guillain-Barré syndrome, after administration of RSVpreF or RSVPreF3 vaccines in adults 60 years of age and older. Information currently available is insufficient to determine if there is an increased frequency of these events associated with the vaccines. NACI will continue to carefully monitor the evidence on the safety of RSVpreF and RSVPreF3 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 palivizumab and nirsevimab, and the active immunizing agents, RSVpreF and RSVPreF3, 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 palivizumab or nirsevimab, 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, palivizumab and RSVpreF vaccine.
Contraindications and precautions
Nirsevimab, palivizumab, and RSVpreF and RSVPreF3 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 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) Statement on the prevention of respiratory syncytial virus (RSV) disease in older adults.
Acknowledgments
This chapter has been revised based on the NACI Statement on the prevention of respiratory syncytial virus (RSV) disease in older adults prepared by N Brousseau, A Killikelly and W Siu on behalf of the NACI RSV Working Group. The chapter was prepared by F Crane, and reviewed by E Abrams, C Jensen, and N Brousseau.
The CIG gratefully acknowledges the contribution of: N Haddad and A Howarth.
Selected references
Abrams EM, Doyon-Plourde P, Davis P, Brousseau N, Irwin A, Siu W, et al. Burden of disease of respiratory syncytial virus in infants, young children and pregnant women and people. Canada Communicable Disease Report. 2024 Feb; 50(1/2):1-15. https://doi.org/10.14745/ccdr.v50i12a01
American Academy of Pediatrics. Respiratory Syncytial Virus. In: Kimberlin DW, Barnett ED, Lynfield R, Sawyer MH (Eds). Redbook: 2021 Report of the Committee on Infectious Diseases. Itasca IL. American Academy of Pediatrics: 2021. (pp 628-636).
AstraZeneca Canada Inc. Product monograph - SYNAGIS®July 9, 2021.
Sanofi Pasteur Limited. Product monograph – Beyfortus® April 19, 2023.
Health Canada. Canada Vigilance Program. Accessed: December 02, 2022 from https://www.canada.ca/en/health-canada/services/drugs-health-products/medeffect-canada/canada-vigilance-program.html
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National Advisory Committee on Immunization. An Advisory Committee Statement: Statement on the prevention of respiratory syncytial virus (RSV) disease in infants. May 17, 2024. Accessed May 17, 2024 from: https://www.canada.ca/en/public-health/services/publications/vaccines-immunization/national-advisory-committee-immunization-statement-prevention-respiratory-syncytial-virus-disease-infants.html
National Advisory Committee on Immunization. An Advisory Committee Statement: Statement on the prevention of respiratory syncytial virus (RSV) disease in older adults. August 9, 2024. Accessed August 9, 2024 from: https://www.canada.ca/en/public-health/services/publications/vaccines-immunization/national-advisory-committee-immunization-statement-prevention-rsv-disease-older-adults.html
National Advisory Committee on Immunization. An Advisory Committee Statement: Recommended use of Palivizumab to Reduce Complications of Respiratory Syncytial Virus Infection in Infants. June 1, 2022. Accessed November 25, 2022 from: https://www.canada.ca/content/dam/phac-aspc/documents/services/publications/vaccines-immunization/palivizumab-respiratory-syncitial-virus-infection-infants/palivizumab-resp-infection-infants-eng.pdf
Pfizer Canada Product monograph – AbrysvoTM December 21, 2023.
Public Health Agency of Canada. Respiratory Viruses Detections in Canada. Accessed March 2024 from: https://www.canada.ca/en/public-health/services/surveillance/respiratory-virus-detections-canada.html
Walsh E, Marc GP, Zareba A, et al. Efficacy and safety of a bivalent RSV prefusion F vaccine in older adults. The New England Journal of Medicine. 2023 Apr 20;388(16):1465-1477. http://doi.org/10.1056/NEJMoa2213836
Footnotes
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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.
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