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Influenza Vaccine

The yearly flu vaccine — free for everyone 6 months and older in Ontario

Quick Summary

Influenza Vaccine (Flu Shot)

A yearly vaccine that protects against the influenza viruses circulating that season.

Seasonal / yearly Publicly funded
Disease Protected Against
Influenza ("the flu") — a respiratory illness that can be more serious in young children, older adults, and those with certain conditions.
Ontario Timing
Once each year, usually in the fall, for everyone 6 months of age and older. Some young children need two doses the first year.
Number of Doses
One dose per season for most; children under 9 getting the flu vaccine for the first time may need two doses, about 4 weeks apart.
Publicly Funded Status
Yes — free for everyone 6 months and older who lives, works, or attends school in Ontario.
Bottom line: The flu vaccine is given every year because the viruses change and protection fades between seasons. In Ontario it's free for everyone 6 months and older through the Universal Influenza Immunization Program. It is not required for school, but it's recommended yearly — especially to protect young children and to reduce spread to vulnerable people, including babies under 6 months who are too young to be vaccinated.
This guidance can change each season. Influenza vaccine products, eligibility, and recommendations are updated yearly by age, risk group, and availability. Check current Ontario and Canadian guidance, or speak with a healthcare provider or local public health unit, before making decisions for the current season.
The Disease

What it protects against

Influenza ("the flu") is a respiratory illness caused by influenza viruses. It's often more than "just a cold," and can be more serious in young children.

Aspect What parents might notice How it spreads Why it can be serious How vaccination helps
Influenza illness Sudden fever, cough, sore throat, body aches, headache, tiredness, and sometimes vomiting or diarrhea in young children. It tends to come on faster and hit harder than a common cold. Mainly through respiratory droplets from coughing and sneezing, and by touching contaminated surfaces. It spreads easily, especially in schools and households. Most children recover, but flu can lead to complications such as pneumonia, ear infections, worsening of conditions like asthma, dehydration, and, less commonly, hospitalization — and it can be dangerous for babies and people with certain health conditions. The vaccine reduces the chance of getting the flu and, importantly, reduces the severity and complications if illness does occur.
Influenza viruses change from year to year, and the protection from a previous season fades. That's why a new vaccine is offered each year, designed to match the strains expected to circulate that season. (For the current season, vaccines protect against three strains.)
Timing & Schedule

Why it's given every year

Why every year? Unlike most vaccines, the flu vaccine is needed annually for two reasons: the influenza viruses change from season to season, and the protection from the vaccine fades over several months. Each year's vaccine is updated to match the strains expected to circulate, and a fresh dose restores protection for the season ahead.

When in the year? The vaccine is usually offered in the fall, before flu activity picks up. It's available free to everyone 6 months and older in Ontario. Getting it in the fall provides protection through the typical flu season, though it's still worth getting later if you miss the fall.

Why might my young child need two doses? Children under 9 who are getting the flu vaccine for the first time ever are recommended to have two doses, given about 4 weeks apart, to build adequate protection that first season. After that first year, one dose per season is enough. A healthcare provider can confirm whether your child needs one or two doses.

Why not for babies under 6 months? The flu vaccine isn't authorized for infants younger than 6 months, because it doesn't work well in that age group. This is one reason it's recommended that everyone around a young baby — parents, siblings, caregivers — be vaccinated, to form a protective "cocoon" around the infant.

Can it be given with other vaccines? Yes. The flu vaccine can be given at the same time as, or any time before or after, other vaccines — including COVID-19 and RSV products. They're given at different sites.

The nasal spray option: Besides the injectable flu vaccine, there's a nasal-spray version (FluMist) — a live attenuated vaccine sprayed into the nose, authorized for ages 2 to 49. It's a needle-free option for many healthy children, but it's not recommended for everyone (for example, those who are pregnant, have weakened immune systems, or have certain conditions like severe asthma). A healthcare provider can advise whether the shot or the nasal spray is the better fit for your child.
Ontario School & Reporting Status

School and reporting status

Influenza is not one of the diseases required for school attendance under Ontario's Immunization of School Pupils Act (ISPA). The flu vaccine is offered free to everyone 6 months and older through the Universal Influenza Immunization Program, and is recommended yearly — but it is not on the ISPA list, so it is not required for school entry.

Influenza is not an ISPA-designated disease for school attendance, so missing it does not trigger the ISPA suspension process. It remains recommended each year because it reduces illness, missed school, and the chance of serious complications — and because vaccinating children also helps protect more vulnerable people around them, including infants too young to be vaccinated.

Reporting: The flu vaccine is given in many places — doctors' offices, pharmacies (often for older children), and public health clinics. Keep a note of each year's dose on your child's record. Because it's seasonal and widely available, it's not tracked for school in the way ISPA-required vaccines are.

Higher-risk children: The flu vaccine is especially encouraged for children with conditions like asthma, heart disease, diabetes, or weakened immune systems, who are at greater risk of complications. A healthcare provider can advise on the best option (for example, the shot rather than the nasal spray for some).

Ingredient Transparency

What's in this vaccine

Several flu vaccine products are used in Ontario. The most common for children are injectable, inactivated vaccines (such as FluLaval®, Fluzone®, Fluarix®, or the egg-free Flucelvax®), authorized from 6 months of age. There's also a nasal-spray live vaccine (FluMist®) for ages 2–49. The information below reflects the general categories of ingredients from their Health Canada product monographs; exact contents vary by product.

Ingredient / Component Category Why it's there Plain-English explanation
Influenza virus antigens (inactivated, in the shot; weakened/live, in the nasal spray) Active ingredients Train the immune system to recognize the season's influenza strains. In the injectable vaccine, the virus is inactivated (killed) or only pieces of it are used — it cannot cause the flu. The nasal spray uses a weakened live virus adapted to the cooler nose, which also doesn't cause true flu in healthy people.
Egg proteins (trace; in egg-based products) Manufacturing residual / potential allergen Many flu vaccines are grown in eggs, so trace egg protein may remain. Most people with egg allergy can still receive flu vaccine safely; egg-free options (like Flucelvax) also exist. Mention an egg allergy to your provider, who can advise.
Sodium chloride and buffer salts Tonicity agent / buffers Keep the vaccine at a stable, body-friendly concentration and acidity. Ordinary salt and small amounts of stabilizing salts.
Stabilizers (e.g. sucrose, gelatin in the nasal spray) Stabilizers Help keep the vaccine stable. Sugars and, in the nasal spray, gelatin — relevant for anyone with a severe gelatin allergy.
Formaldehyde (trace amounts) Manufacturing process residual Used in making some inactivated vaccines; trace amounts may remain. Any remaining amount is very small — less than the body naturally produces during normal metabolism.
Thimerosal (only in some multi-dose vials) Preservative Prevents contamination in multi-dose vials. The single-dose syringes commonly used for children are preservative-free. Multi-dose vials may contain a small amount of this preservative; an alternative can be requested.
Egg allergy: Having an egg allergy generally does not prevent a child from getting a flu vaccine — current guidance is that people with egg allergy can receive any age-appropriate flu vaccine. Egg-free products also exist. Each season's exact products and formulations can change — for the specific contents of the vaccine your child receives, ask your provider or check the product monograph.
Side Effects & Safety

Side effects and safety

Expected / common side effects

  • Soreness, redness, or swelling where the needle was given
  • Mild fever
  • Irritability or fussiness
  • Drowsiness or sleepiness
  • Decreased appetite

Timing and duration: These reactions usually begin within a day of the vaccine and typically resolve within 1–2 days.

Home care: A cool compress can ease injection-site soreness. Acetaminophen or ibuprofen may be used as directed for discomfort or fever — check with a pharmacist or healthcare provider on appropriate dosing for your child's age and weight. Children under 19 should not be given ASA (Aspirin) or salicylate-containing products.

When to call a healthcare provider: If a fever is high or persistent, if your child seems unusually unwell, or if you're unsure — it's always reasonable to call.

Mild side effects can happen as the immune system responds. Many children have no side effects at all, and that does not mean the vaccine didn't work.

Rare but important

  • Severe allergic reaction (anaphylaxis) — reported rarely after vaccination in general; exact frequency varies by source.
  • Febrile seizure — a seizure triggered by fever, which can happen with any fever-causing illness or vaccine in young children. Uncommon and usually brief.
  • Nasal spray: the nasal-spray version can cause transient runny nose or congestion, and isn't recommended for certain groups (see "who should pause" below).

The flu vaccine cannot give you the flu: The injectable vaccine contains no live virus, and the nasal spray uses a weakened virus that can't cause true influenza in healthy people. Feeling a bit run-down for a day is the immune system responding — not the flu itself.

What clinics do to reduce risk: Clinics ask about allergy history before vaccination and are equipped with epinephrine and trained staff in case of a severe allergic reaction.

Observation period: Staying nearby for about 15 minutes after vaccination is recommended, as severe allergic reactions — though rare — typically occur shortly after.

Get urgent help now if your child has:

  • Trouble breathing
  • Swelling of the lips, tongue, throat, or face
  • Widespread hives together with breathing difficulty
  • Severe weakness, limpness, or unresponsiveness
  • A seizure
  • Persistent, inconsolable crying that won't settle, or you are very worried
  • A high or persistent fever, especially in a young infant
  • Any symptom that feels serious or is rapidly getting worse

If any of these occur, go to the nearest emergency department or call 911. Otherwise, contact a healthcare provider and let them know what happened — this information also helps with vaccine safety monitoring.

Before the Appointment

Who should pause or speak with a healthcare provider first

Speak with a healthcare provider before this vaccine if:

  • Your child has had a serious allergic reaction to a previous dose of flu vaccine, or to any component
  • Your child has a severe egg allergy — most can still be vaccinated safely, but a provider may advise on which product or setting
  • Your child has a moderate or severe acute illness (it's generally fine to wait until they feel better)
  • For the nasal spray specifically: if your child is under 2, has a weakened immune system, has severe asthma or recent wheezing, is pregnant, or is on certain medications — the injectable vaccine is used instead

These usually do NOT require delaying this vaccine:

  • A mild cold or other minor illness without fever
  • Mild egg allergy (any age-appropriate flu vaccine can generally be given)
  • Currently breastfeeding
  • A stable, ongoing chronic health condition (in fact, often a reason it's more strongly recommended)
  • Currently taking antibiotics for an unrelated condition
Common Questions

Questions parents often ask

Two reasons: the flu viruses change from year to year, so each season's vaccine is updated to match the expected strains; and the protection fades over several months. A yearly dose keeps protection current and matched to what's circulating.
No. The injectable flu vaccine contains no live virus, and the nasal spray uses a weakened virus that can't cause true flu in healthy people. Some children feel a little run-down for a day as their immune system responds — that's not the flu. People can also catch an unrelated cold around the same time and mistake it for a vaccine reaction.
Both protect well. The nasal spray (FluMist) is a needle-free option for many healthy children aged 2–49, which some families prefer. The injectable vaccine is used for those under 2 and for anyone for whom the spray isn't recommended (such as severe asthma, weakened immune system, or pregnancy). A healthcare provider can help you choose.
Generally, no. A mild cold without fever is usually not a reason to delay. If your child has a fever or seems more unwell, it's reasonable to mention this to the clinic — they can advise whether to proceed or reschedule.
A mild fever after a previous dose is common and is not usually a reason to avoid future doses. Let the clinic know about the previous reaction — they can advise on any precautions, such as giving acetaminophen proactively, and will watch for any pattern.
In almost all cases, yes. Current guidance is that people with egg allergy — even severe — can receive any age-appropriate flu vaccine. There are also egg-free products (like Flucelvax). Let the provider know about the allergy, and they'll advise on the best option and any precautions.
The flu vaccine is widely available each fall — through family doctors and nurse practitioners, public health clinics, and many pharmacies (pharmacists can often vaccinate children, depending on age). It's free for everyone 6 months and older in Ontario. See the Resources page for links to find a location.
Parents and caregivers are generally responsible for reporting vaccines to their local public health unit — healthcare providers do not always do this automatically. Many areas use Immunization Connect Ontario (ICON) for this. See the Resources page for links.
Mild soreness, redness, fussiness, or a low fever for a day or two are common and expected. Review the "Get urgent help now" list above — if any of those signs occur, seek urgent care. Otherwise, contact a healthcare provider with any concerns.
What the Evidence Shows

What we know about the flu vaccine

Fact The flu vaccine's effectiveness varies from year to year depending on how well it matches the circulating strains — but even in years with a less-than-perfect match, it reduces the chance of serious illness and hospitalization.
Concern Some parents have heard that "the flu shot doesn't always work," and wonder whether it's worth getting if it isn't 100% effective.
Evidence It's true that flu vaccine effectiveness isn't as high as some other vaccines, and varies by season. But "not perfect" isn't the same as "not worth it": vaccinated children who do catch flu tend to have milder illness and fewer complications, and studies have shown meaningful reductions in flu hospitalizations in children. Because the flu can be serious and spreads easily, even partial protection has real value — for the child and for the vulnerable people around them.
Takeaway The flu vaccine meaningfully lowers the chance of serious flu illness each season, even when the match isn't perfect — which is why it's recommended yearly.
Fact Vaccinating children against flu also helps protect people who are more vulnerable, including babies under 6 months who are too young for the vaccine.
Concern Some parents feel that a healthy child doesn't really need a flu vaccine.
Evidence Even healthy children can get seriously ill from flu, and they're also efficient spreaders of it. Vaccinating children reduces illness in the child and helps limit spread to grandparents, newborn siblings, and others at higher risk. This "community protection" effect is part of why broad childhood flu vaccination is encouraged.
Takeaway Flu vaccination protects the individual child and contributes to protecting more vulnerable people nearby — a benefit beyond the child alone.
Ontario Next Steps

What to do next

Where to get it

Each fall: family doctors, nurse practitioners, public health clinics, and many pharmacies. Free for everyone 6 months and older in Ontario.

When to get it

Usually in the fall, before flu season picks up — but worth getting later if you miss the fall, since flu can circulate into spring.

What to bring / mention

Your child's record, and a note of any egg or other allergies, asthma, or whether this is their first-ever flu vaccine (which may mean two doses).

Shot or nasal spray?

Ask your provider which is right for your child. The nasal spray is needle-free for many healthy kids 2+, but isn't for everyone.

Pair with other vaccines

The flu vaccine can be given at the same visit as COVID-19, RSV, or routine vaccines — convenient for one trip.

Keep a record

Note each year's flu dose on your child's record. See the Resources page for finding clinics and pharmacies.

Sources

Where this information comes from

This page is based on:

Last reviewed: June 2026  ·  Next review due: December 2026
Schedules, products, and eligibility can change. Always confirm current details with your healthcare provider, your local public health unit, or official Ontario sources.

Please note: This is an independent website. It is not affiliated with, endorsed by, or operated by the Government of Ontario, the Ministry of Health, or any public health unit. The information here is for general education only and is not medical advice — always consult a licensed healthcare provider about your or your child's immunizations.