Avian Influenza

Home / Avian Influenza

What is the Arepanrix™ H5N1 vaccine?

Arepanrix™ H5N1 is a vaccine that has been approved for use by Health Canada for immunization against avian influenza A(H5N1) infection in adults and children ages 6 months of age and older. This vaccine contains modified and inactivated virus and cannot make you sick by giving you A(H5N1). This vaccine helps your immune system create antibodies that fight avian influenza A(H5N1) infection.

Arepanrix™ H5N1 is not a treatment for avian influenza infection. It should be used to protect against infection and disease. You should not receive the vaccine if you are experiencing any symptoms of influenza, and it is important to let your health care provider know if you are having symptoms so that testing can be arranged.

When should the Arepanrix™ H5N1 vaccine be given?

Ideal timing for receiving this vaccine series is over the summer of 2025. This will allow for protection ahead of the fall bird migration season when detections of avian influenza increase. Doses of H5N1 vaccine should be given at least 6 weeks apart from other vaccine doses, so a summer vaccine series will allow for enough time separation ahead of when seasonal influenza vaccine doses will be available this fall.

Who should get the Arepanrix™ H5N1 vaccine?

Based on the current context (i.e., no human-to-human transmission and not in a pandemic state) and the risk of exposure in Ontario, the following individuals are eligible to receive this vaccine series to protect against human infection with avian influenza A(H5N1) given ongoing and significant exposure to infected animals and the virus:

People who handle live avian influenza A(H5N1) virus in laboratory settings.

  • Examples include laboratory workers who manipulate, handle, or culture live avian influenza A(H5N1) virus such as in research, industrial, or clinical reference laboratory settings.

People with ongoing contact with known infected birds or other infected animals.

  • Wildlife officers, researchers, rehabilitators who handle dead or sick birds or mammals (e.g., bird banders).
  • Veterinarians or veterinary technicians who are exposed to dead or sick birds or mammals with avian influenza A(H5N1) (e.g., necropsy).

Vaccine is voluntary and optional and should be offered to eligible individuals after a risk/benefit discussion regarding the vaccine and the limited data on effectiveness of protection against avian influenza A(H5N1), duration of effectiveness, potential for impacts on future H5N1 pandemic vaccines.

Other individuals, for example hunters and trappers, may interact with birds or animals that could be infected with H5N1. However, as their role is generally interacting with live and well birds and animals, they are at much lower risk of exposure compared to those with an occupational risk of handling sick or dead birds and animals. Therefore, only the listed occupationally exposed groups are eligible. Eligible populations may change over time if the context and risk change.

How many doses of the Arepanrix™ H5N1 vaccine is needed to achieve protection?

Arepanrix™ H5N1 is a two-dose vaccine series. The second dose should be given at least three weeks (21 days) after the first dose.

Can the Arepanrix™ H5N1 vaccine be given at the same time as other vaccines?

It is preferable to have an interval of at least 6 weeks separating a dose of Arepanrix™ H5N1 and any other vaccine, including the seasonal influenza vaccine, unless the vaccine is needed urgently. This recommendation is precautionary to prevent potential misattribution of an adverse event following immunization (AEFI) to a vaccine.

Should individuals who receive the Arepanrix™ H5N1 vaccine still receive the seasonal influenza vaccine this fall?

Eligible individuals who may receive the Arepanrix™ H5N1 vaccine should still be recommended to receive their seasonal influenza vaccine this fall. While seasonal influenza vaccine does not protect against avian influenza, it can reduce the risk of an individual being infected with both seasonal influenza and avian influenza at the same time.

What is the effectiveness of the vaccine?

There are no direct studies of immunogenicity or effectiveness of the Arepanrix™ H5N1 (A/American wigeon clade 2.3.4.4b) vaccine; however, there is indirect evidence from Arepanrix™ H5N1 (A/Indonesia clade 2.1.3.2), and from Arepanrix™ H1N1 and Pandemrix™ H1N1 vaccines.

Immunogenicity against homologous strain (vaccine strain) based on (A/Indonesia) found seroprotection rates (defined as the proportion of subjects with a hemagluttinin inhibition assay titre ≥1:40) ranges from 76.8 to 91.0% 21 days after second dose and remained between 62.2 to 63.5% six months after the start of the series. There is some cross-reactive response to heterologous (non-vaccine) strains of H5N1, but responses were much lower compared to homologous strains. Immune responses were stronger against heterologous strains in the same clade versus against different clades.

How is the Arepanrix™ H5N1 vaccine administered?

Adult dosage is 0.5mL intramuscularly.

The vaccine consists of two containers: one multidose vial containing the antigen (suspension) and a second multidose vial containing the adjuvant system (emulsion).  Product should be stored in vaccine refrigerator between 2C to 8C, do not freeze. Prior to mixing the two components they must be brought to room temperature (allow a minimum of 15 minutes after removing from the fridge). The adjuvant then must be added to the antigen vial and mixed thoroughly by inversion.

Once mixed, the vial (5mL) contains 10 doses (0.5mL each). The vaccine must be used within 24 hours.  The mixed vaccine can either be stored in the refrigerator (2C to 8C) or at room temperature (up to 30C). If kept in the fridge, it must be allowed to reach room temperature before each withdrawal.  Any unused product should be disposed of after 24hours from mixing.How is the Arepanrix™ H5N1 vaccine administered?

Who should not receive this vaccine?

Arepanrix™ H5N1 should not be given to people who have allergies to any of the ingredients in the vaccine.  Potential allergens include trace egg protein, Polysorbate 80, and thimerosol.

A history of an anaphylactic reaction (i.e. life-threatening) to any of the constituents or trace residues of the vaccine, including egg protein, is a contraindication.

Can individuals who are pregnant or breastfeeding receive this vaccine?

No data have been generated for this specific vaccine for pregnant or breast-feeding individuals.

Data from vaccinations with similar vaccine formulations for seasonal influenza vaccines in pregnant individuals do not indicate that adverse fetal and maternal outcomes were attributable to the vaccine.

Does this vaccine have side effects?

Vaccines, like all medications, can have side effects. Rarely, allergic reactions can occur after receiving a vaccine.  Seek immediate medical care if you develop any symptoms of an allergic reaction, including hives (bumps on the skin that are often very itchy), swelling of your face, tongue or throat, or difficulty breathing.

More commonly, people can experience mild to moderate pain, redness, swelling at the injection site, or muscle aches, headache and/or fatigue for a few days after receiving the vaccine.

Any severe, unexpected, or unusual adverse events following the receipt of the Arepanrix™ H5N1 vaccine, whether or not they are clearly attributable to the vaccine, should be reported to the local public health unit.

When should I call my doctor?

Serious reactions after vaccination are very rare.  Get immediate medical help if you/your child have any unusual symptoms such as:

  • trouble breathing, swelling in your face/mouth and/or blotchy skin (hives)
  • fever above 40°C (104°F);
  • crying or fussing for more than 24 hours (infants/young children);
  • worsening swelling, redness, and/or pain where the needle went in;
  • unusual sleepiness (difficult to wake)

You know best.  If you notice anything that is not normal after a vaccination, check with your healthcare provider.

Talk to your healthcare provider if you have any questions.

Remember: Make sure to update your immunization record

This information is for general knowledge only and does not replace professional medical advice. Please note there is a cost for immunizations that are not included in Ontario's routine immunization schedule | ontario.ca 

For more information contact us at:

Reproduced with the permission of Wellington-Dufferin-Guelph Public Health

No data have been generated for this specific vaccine for pregnant or breast-feeding individuals.

Data from vaccinations with similar vaccine formulations for seasonal influenza vaccines in pregnant individuals do not indicate that adverse fetal and maternal outcomes were attributable to the vaccine.