Updated Canadian guidance on use of RSV vaccines in older adults

The National Advisory Committee on Immunization has issued updated guidance on the use of respiratory syncytial virus (RSV) vaccines for older adults.1,2 The statement updates an earlier version published in July 2024.3 The update includes information on the third RSV vaccine to become available in Canada—the first RSV mRNA vaccine (mResvia, Moderna). It also incorporates an expanded age range for use of Arexvy (GSK). Three RSV vaccines are now approved in Canada:RSVpreF (Abrysvo, Pfizer), a stabilized subunit vaccine (marketed)RSVPreF3 (Arexvy, GSK), a stabilized subunit AS01E adjuvanted vaccine (marketed)mRNA-1345 (mResvia, Moderna), an mRNA vaccine (expected to be available in the first half of 2025).All three vaccines are indicated for the prevention of lower respiratory tract disease (LRTD) caused by RSV in adults 60 years of age or older. Arexvy was also recently approved for adults 50–59 years of age at increased risk for RSV disease. In addition, Abrysvo is indicated for active immunization of pregnant individuals from 32–36 weeks gestational age for the prevention of LRTD and severe LRTD caused by RSV in infants from birth through six months of age. Summary of NACI recommendations on use of RSV vaccines in older adults1,21. NACI continues to recommend RSV immunization programs for adults ≥ 75 years of age, particularly for older adults at increased risk of severe RSV disease. (Strong NACI recommendation)Clinically significant chronic health conditions for which RSV vaccination is particularly important include: cardiac or pulmonary disorders (includes chronic obstructive pulmonary disease, asthma, cystic fibrosis, and conditions affecting ability to clear airway secretions); diabetes and other metabolic diseases; moderate and severe immunodeficiency; 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); and class 3 obesity (defined as BMI ≥ 40 kg/m2). 2. NACI continues to recommend RSV immunization programs for adults 60 years of age or older who are residents of nursing homes or other chronic care facilities. (Strong NACI recommendation)For recommendations #1 and #2:A single dose of Arexvy, Abrysvo or mResvia can be used. NACI judged that all three vaccines work well, but less data are available for the safety and efficacy of mResvia.NACI acknowledges concerns regarding the storage temperature for mResvia (frozen between -40°C to -15°C for up to 18 months; refrigerated for a maximum of 30 days; 8°C–25°C for a total of 24 hours). Jurisdictions should weigh the storage conditions when considering product selection.Uncertainty still exists about the duration of protection and the need for and timing of any potential booster doses with any of three authorized RSV vaccines.All three vaccines are safe and well tolerated. Preliminary data indicate that the risk of Guillain-Barré syndrome (GBS) may be increased following Arexvy and Abrysvo in older adults. Studies with more robust designs to further evaluate GBS risk are planned.3. NACI recommends that RSV vaccines may be considered as an individual decision by adults 50–74 years of age with their healthcare provider. (Discretionary NACI recommendation) Any of the three RSV vaccines can be used in adults 60–74 years of age.Arexvy can be used in adults 50–74 years of age. For adults 50–59 years of age, there are no efficacy data for Arexvy; immunogenicity findings show that Arexvy elicits a noninferior immune response in adults 50–59 years of age compared to adults 60 years of age or older.Vaccination has more benefits for individuals who are at increased risk of severe RSV disease (see list of medical conditions that increase risk, below Recommendation #1).Uncertainty exists about the duration of protection and the need for and timing of any potential booster doses. Concurrent administration with other vaccinesConcurrent administration of these three (non-live) RSV vaccines with other vaccines can be considered, based on the basic vaccine principle that non-live vaccines may generally be administered concurrently with, or at any time before or after, other vaccines. However, if possible, RSV vaccines should be given at least six weeks before or after nonseasonal vaccines (e.g., shingles, diphtheria-tetanus vaccines) to avoid inadvertently attributing an adverse event from another vaccine to the RSV vaccine or vice versa.2 Additional research is ongoing related to same-day administration of RSV vaccines and other adult vaccines, including COVID-19 vaccines, as well as the co-administration of two mRNA vaccines targeting different pathogens and same-day administration of two adjuvanted vaccines targeting different pathogens.2Other key information in the updateThe updated NACI statement includes a table summarizing the characteristics of the three RSV vaccines approved in Canada, including vaccine adjuvant, composition, dosage schedule, indications, contraindications, precautions and storage requirements. Detailed discussion is also provided on mResvia vaccine efficacy, RSV vaccine effectiveness and immunogenicity, RSV vaccine safety (including local, systemic and serious adverse events) and post-marketing safety data. Cost-effectiveness is also addressed.2 Research prioritiesNACI is encouraging research to address the following outstanding issues:Clarify any similarities and differences between RSV vaccines using different vaccine platforms (i.e., protein subunit vs mRNA)Determine RSV vaccine efficacy in adults 18 years of age and older with medical conditionsDetermine whether RSV vaccines prevent cardiovascular events, especially in individuals with pre-existing cardiac disordersDetermine duration of protection for RSV vaccines in older adultsEstablish the long-term implications of RSV vaccines for older adults, including whether or not boosting can be achieved (and if so, determine the optimal interval between doses)Verify the safety of RSV vaccines outside of the clinical trial settingDetermine whether an association exists between GBS and RSV vaccination, and the safety of RSV vaccines in patients with a history of GBSExamine the safety and efficacy of concurrent administration of RSV vaccines and other vaccines in older adults.2ReferencesNational Advisory Committee on Immunization. Summary of NACI statement of March 13, 2025: updated guidance on respiratory syncytial virus (RSV) vaccines for older adults including the expanded use of RSVPreF3 for individuals 50 to 59 years of age and use of the new mRNA-1345 vaccine. (accessed March 18, 2025).National Advisory Committee on Immunization (NACI). An Advisory Committee Statement (ACS). Updated guidance on respiratory syncytial virus (RSV) vaccines for older adults including the expanded use of RSVPreF3 for individuals 50 to 59 years of age and the use of the new mRNA-1345 vaccine. March 13, 2025. [this full statement is not yet published online, but can be requested from naci.publications-ccni@phac-aspc.gc.ca]National Advisory Committee on Immunization (NACI). An Advisory Committee Statement (ACS). Statement on the prevention of respiratory syncytial virus (RSV) disease in older adults. July 2024. (accessed March 18, 2025).

Updated Canadian guidance on use of RSV vaccines in older adults

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