Summary of NACI statement of July 25, 2024: Statement on seasonal influenza vaccine for 2024–2025

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• Overview
• What you need to know

Overview

• On July 25, 2024, the Public Health Agency of Canada (PHAC) released the National Advisory Committee on Immunization (NACI) Statement on Seasonal Influenza Vaccine for 2024-2025. This guidance is based on current evidence and NACI expert opinion and is updated every year.
• A seasonal influenza vaccine is one of the most effective ways to prevent influenza and its complications and is an important component of managing health care system capacity during the respiratory virus season. The influenza vaccine can also help prevent the spread of the virus to others.
• Seasonal influenza vaccines have proven safety profiles and are approved for everyone who is 6 months of age and older.

Following a thorough review of evidence, NACI continues to recommend that:

• Any age appropriate quadrivalent or trivalent influenza vaccine should be used for individuals 6 months of age and older who do not have contraindications or precautions. Immunization is particularly important for the following groups:
  • People at high risk of severe disease, influenza-related complications, or hospitalization
    • Children 6 months up to 5 years of age
    • Adults 65 years of age and older
    • Adults and children with certain chronic health conditions
    • Individuals who are pregnant
    • People of any age who are residents of nursing homes and other chronic care facilities
    • Indigenous peoples
  • People capable of transmitting influenza to those at high risk
    • Health care and other care providers in facilities and community settings
    • Household contacts (both adults and children) of individuals at high risk (as noted above) as well as of infants less than 6 months of age and members of a household expecting a newborn during the influenza season
    • Those providing regular child care to children under the age of five, whether in or out of the home
    • Those who provide services within closed or relatively closed settings to people at high risk (e.g., crew on a cruise ship)
  • People who provide essential community services
  • People in direct contact with poultry potentially infected with avian influenza during culling operations
• A seasonal influenza vaccine should be prioritized for the groups for whom influenza vaccination is particularly important.
• The full list of individuals at high risk of influenza-related complications or hospitalization and individuals capable of transmitting influenza to those at high risk can be found within the statement.
• This statement includes updated and new, detailed guidance on influenza vaccination during pregnancy and influenza vaccination in adults 65 years of age and older. This updated guidance provides tailored advice and reinforces the importance of influenza vaccine for these groups.
• NACI will continue to monitor the evolving evidence related to influenza vaccines and will update guidance as needed.

For the full statement, including supporting evidence and rationale, please see NACI's Statement on Seasonal Influenza Vaccine for 2024-2025.

What you need to know

• Influenza is a respiratory illness caused by the influenza virus and can cause mild to severe illness, including hospitalization and death.
• Seasonal influenza presents an ongoing health challenge in Canada during the fall and winter months, particularly for young children, older adults, people who are pregnant and people with chronic health conditions, who are all at higher risk for serious influenza complications such as pneumonia. Taking steps to prevent illness, including vaccination, helps to keep individuals healthy, and can reduce hospitalizations due to respiratory illness, which decreases pressure on our health care system.
• The seasonal influenza vaccine is needed every year because protection from the vaccine decreases over time and the strains of the virus that circulate can change from year to year. Before every influenza season, international experts provide advice on the specific strains of influenza viruses that should be included in the vaccine for the upcoming season.
• When children 6 months to less than 9 years of age receive a seasonal influenza vaccine for the first time, they should be given 2 doses one month apart. Afterwards, they only need 1 dose every fall.
• If a seasonal influenza vaccine is given for the first time to an individual 9 years of age or older, only 1 dose is recommended for that year and future years.
• Household contacts of infants younger than 6 months of age, or members of a household expecting a newborn during the influenza season, are recommended to receive the influenza vaccine to help prevent spread to infants younger than 6 months who are at high risk of influenza-related complications but cannot receive the vaccine themselves. In addition, vaccination of the pregnant person can result in immunity being passed to the baby before birth that can help prevent influenza infection and hospitalization for several months after birth.
• Quadrivalent influenza vaccines were previously preferred for children due to the additional protection they provided. However, as the B/Yamagata virus has not been detected globally since March 2020, expert groups have now recommended the exclusion of the B/Yamagata component from influenza vaccine formulations, in alignment with the World Health Organization (WHO) recommendations for the 2024-2025 Northern Hemisphere season. Therefore, NACI no longer has a preference between quadrivalent and trivalent influenza vaccines for children. Both formulations are safe and effective.
• As of July 2024, multiple outbreaks of avian influenza have occurred in poultry and wild birds in Canada and the US, with spillover events in dairy cattle in the US.
  • This virus has also spread to numerous other mammals.
• In the US, humans have acquired mild infections from cows and poultry. NACI reiterates its recommendation that all individuals 6 months of age and older should receive an authorized, age-appropriate seasonal influenza vaccine, including all those who are likely to have significant exposure to animal influenza viruses through interactions with birds or mammals (such as poultry, livestock, slaughterhouse and processing plant workers, wildlife officers/researchers, and veterinarians).
  • Infection with both animal influenza (such as avian influenza) and human influenza virus could theoretically lead to genetic changes of the virus and an influenza strain that could pose greater risk to human health. Although seasonal influenza vaccination will not prevent animal influenza (such as avian influenza) infection, it may reduce the risk of getting both viruses at the same time.
• NACI is conducting an evidence review to determine whether other people who have significant exposure to animal influenza viruses through their work or other activities should be permanently added to the list of groups for whom influenza vaccination is particularly important.
• Any seasonal influenza vaccine may be given at the same time as, or any time before or after, administration of other vaccines, including COVID-19 vaccines.
• There are several influenza vaccines authorized for use in Canada, some of which are authorized for use only in specific age groups. Please talk to your healthcare provider or local public health authority to determine which vaccine is available in your province/territory and which is recommended for you.

For more information on NACI recommendations related to seasonal influenza vaccination, please see the Canadian Immunization Guide chapter on influenza vaccines, as well as additional statements on the NACI web page.