Flucelvax: Uses, Side Effects and Dosage

What is FLUCELVAX® used for?

FLUCELVAX® is used in adults and children 6 months and older to prevent influenza, often called “the flu.”

Influenza is caused by infection with specific influenza viruses. New types of influenza viruses can appear each year. FLUCELVAX® vaccine contains fragments of three different types of influenza virus. Each year the World Health Organization decides which three types of viruses are most suitable to include in the vaccine.

For this season (2026 – 2027) the viruses are A/Missouri/11/2025 (H1N1)pdm09-like virus, A/Darwin/1415/2025 (H3N2)-like virus, and B/Pennsylvania/14/2025-like virus.

You cannot catch influenza from the vaccine, as the virus in the vaccine has been killed and split into small non-infectious particles.

The National Advisory Committee on Immunization (NACI) encourages annual influenza vaccination for all Canadians who are able to have the vaccine.

Vaccination against influenza is recommended every year, for anyone wanting to lower their chance of catching influenza. FLUCELVAX® has been used by many people to lower their risk of catching the flu.

How does FLUCELVAX® work?

FLUCELVAX® vaccine works by helping your body to protect itself against infection by the types of influenza viruses that are in the vaccine. The vaccine stimulates the body to make substances called antibodies. Antibodies fight the influenza virus. If you have been vaccinated, when you come into contact with the influenza viruses in the vaccine, your body is usually able quickly to destroy the virus, which may prevent you from getting influenza.

Your body takes a few weeks after vaccination to fully develop effective protection against the influenza virus.

Protection against influenza generally requires one dose of FLUCELVAX® vaccine, however, some children less than 9 years of age may require two doses (see section Usual dose).

As with all vaccines, 100% protection cannot be guaranteed.

What are the ingredients in FLUCELVAX®?

Medicinal ingredients:

Each 0.5 mL dose of the vaccine contains 15 mcg haemagglutinin (HA) from each influenza strain:

• A/Missouri/11/2025 (H1N1)pdm09-like virus (A/Tasmania/318/2025 CVR-351)
• A/Darwin/1415/2025 (H3N2)-like virus (A/Tasmania/787/2025 CVR-388)
• B/Pennsylvania/14/2025-like virus (B/Arizona/21/2025)

Non-medicinal ingredients:

• Beta-propiolactone**,
• Cetyltrimethylammonium bromide**,
• Disodium phosphate dihydrate,
• Magnesium chloride hexahydrate,
• Polysorbate 80**,
• Potassium chloride,
• Potassium dihydrogen phosphate,
• Sodium chloride,
• Thimerosal*,
• Water for injections

*Thimerosal is included in multi-dose vials only.

**Residuals

FLUCELVAX® is not made using eggs, therefore, there are no egg proteins in the vaccine.

The syringe and vial components do not contain latex. FLUCELVAX® is considered safe for use in persons with latex allergies.

FLUCELVAX® pre-filled syringes contain no preservative or antibiotics. FLUCELVAX® multi-dose vial formulation contains a preservative, but does not contain any antibiotics.

FLUCELVAX® comes in the following dosage forms:

FLUCELVAX® is supplied as a suspension for intramuscular injection in either a 0.5 mL single-dose, pre-filled syringe or a 5 mL multi-dose vial.

Do not use FLUCELVAX® if:

• Your child is under 6 months of age. FLUCELVAX® vaccine is only approved for use in children aged 6 months and older.
• You or your child have or previously have had an allergy to FLUCELVAX® or any ingredient listed in this leaflet.

To help avoid side effects and ensure proper use, talk to your healthcare professional before you take FLUCELVAX®. Talk about any health conditions or problems you may have, including if you or your child:

• have or have had a reaction to vaccination with any of the following:

  • severe allergic reaction
  • difficulty breathing
  • swelling of the throat
  • fainting or collapse
  • fits or convulsions
  • high temperature (greater than 38.5°C)
  • severe skin reaction at the injection site, including severe bruising
• have an infection or temperature higher than 38.5°C. Your doctor may decide to delay vaccination until the illness has passed. A minor illness such as a cold is not usually a reason to delay vaccination.
• have low immunity due to treatment with certain medicines
• have or have had Guillain-Barré Syndrome (GBS), an illness which affects the nervous system and causes paralysis.
• have allergies to other medicines or substances

• are pregnant or breastfeeding. Your healthcare professional will be able to discuss the potential risks and benefits of having FLUCELVAX® while you are pregnant or breastfeeding.

• have experienced fainting, or feeling faint, with a previous injection. Fainting can occur following, or even before, any vaccination. Appropriate measures should be taken to prevent injury from falling.

Tell your healthcare professional about all the medicines you take, including any drugs, vitamins, minerals, natural supplements or alternative medicines.

The following may interact with FLUCELVAX®:

No data are available on administration of FLUCELVAX® with other vaccines.

How FLUCELVAX® is given:

FLUCELVAX® is given as an injection into a muscle, usually in the upper arm.

Usual dose:

FLUCELVAX® is given once every year as follows:

• Adults and children 9 years and over: one injection of 0.5 mL.

For children 6 months to less than 9 years old who are receiving influenza vaccine for the first time, it is recommended that a follow-up (booster) dose of FLUCELVAX® is given 4 weeks after the first dose.

If the follow-up dose is missed, talk to your healthcare professional and arrange another visit as soon as possible.

Overdose:

What are possible side effects from using FLUCELVAX®?

These are not all the possible side effects you or your child may experience after receiving FLUCELVAX®. If you or your child experience any side effects not listed here, tell your healthcare professional.

The following are common or very common side effects of FLUCELVAX®. Most of these side effects are mild and do not last long. Tell your doctor if you or your child have side effects that bother you:

• Injection site pain, reddening, hardening or swelling
• Headache
• Muscle or joint pain
• Tiredness
• Nausea, vomiting, diarrhea
• Loss of appetite
• Bruising
• Shivering

Younger children may also experience the following common or very common side effects:

• Injection site tenderness
• Irritability
• Sleepiness
• Change of eating habits.
• Fever

Serious side effects and what to do about them

If you or your child have a troublesome symptom or side effect that is not listed here or becomes bad enough to interfere with your daily activities, tell your healthcare professional.

Storage:

Store in a refrigerator between 2° to 8°C. Do not freeze. Protect from light. Do not use after the expiration date. The multi-dose vial must be used within 28 days from the initial removal of the first dose and between uses, return the multi-dose vial to the recommended storage conditions.

Keep out of reach and sight of children.

If you want more information about FLUCELVAX®:

• Talk to your healthcare professional
• Find the full product monograph that is prepared for healthcare professionals and includes this Patient Medication Information by visiting the Health Canada website: (https://www.canada.ca/en/health-canada/services/drugs-health-products/drug-products/drug-product-database.html; the manufacturer’s website www.seqirus.ca, or by calling 1-855-358-8966.

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