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Varicella Vaccine

Protects against varicella (chickenpox) — Varivax® III or Varilrix®

Quick Summary

Varicella Vaccine (Chickenpox)

Protects against varicella — the virus that causes chickenpox.

Required for school* Publicly funded
Disease Protected Against
Varicella (chickenpox), and it also reduces the risk of shingles later in life.
Ontario Routine Timing
First dose at 15 months. A second dose of varicella protection is given at 4–6 years, usually as MMRV.
Number of Doses
Two doses of varicella-containing vaccine in childhood
Publicly Funded Status
Yes — provided free of charge as part of Ontario's routine schedule
Bottom line: The varicella vaccine prevents chickenpox, which is very contagious and occasionally causes serious complications. The first dose is at 15 months, with a second at 4–6 years (usually as the combined MMRV vaccine). *Varicella is required for school for children born in 2010 or later (unless a valid exemption applies); for older children it's recommended but not part of the school requirement.
The Disease

What it protects against

The varicella vaccine protects against chickenpox — a very contagious illness caused by the varicella-zoster virus.

Disease What parents might notice How it spreads Why it can be serious How vaccination helps
Chickenpox (varicella) An itchy rash of small blisters all over the body, usually with fever and feeling unwell. The blisters scab over as they heal. Extremely contagious — through the air and by contact with the blisters. A person is contagious before the rash even appears. Often mild, but can lead to skin infections, pneumonia, or, less commonly, more serious complications. It tends to be more severe in babies, teens, adults, pregnant people, and those with weakened immune systems. The vaccine prevents most cases of chickenpox, and those who do still get it after vaccination usually have a much milder illness.
Shingles (later in life) A painful rash, usually in a band on one side of the body, caused by the same virus reactivating years later. Not caught from others in the usual sense — it comes from the varicella virus that stays dormant in the body after chickenpox. Can be painful and, in some people, lead to lasting nerve pain. Vaccination against chickenpox is associated with a lower risk of shingles later in life compared with having had wild chickenpox.
Chickenpox was once considered a routine part of childhood, but it isn't always mild — and because it's so contagious, it spreads easily to people who are more vulnerable to complications. Vaccination prevents most cases and reduces spread in the community.
Timing & Schedule

Why it's given at this age

Why at 15 months? The first dose is given at 15 months, after the 12-month vaccines, when a child's immune system responds well and lasting protection can be built. It's part of the cluster of vaccines given in the second year of life.

Why two doses? One dose provides good protection, but a second dose improves it and reduces the chance of "breakthrough" chickenpox (a usually milder case in someone who's been vaccinated). In Ontario, the second dose is typically given at 4–6 years, usually as the combined MMRV vaccine.

What if a dose is late? A delay doesn't mean restarting — the next dose can generally be given at the next opportunity, following minimum spacing. A healthcare provider or public health unit can confirm timing. See the Catch-Up & Missing Records page.

Can it be given with other vaccines? Yes. As a live vaccine, varicella has specific timing considerations relative to other live vaccines (like MMR) — they're either given at the same visit or spaced apart by a minimum interval. A healthcare provider manages this.

What if my child already had chickenpox? A child who has had chickenpox is generally considered to have protection and may not need the vaccine — but this should be confirmed with a healthcare provider, who can review the history and advise. The school requirement can usually be met either by vaccination or by a documented history of the disease (your public health unit can confirm what they accept).
Ontario School & Reporting Status

School and reporting status

Varicella is required for school — for children born in 2010 or later. Under the Immunization of School Pupils Act (ISPA), Ontario requires immunization against varicella for school attendance, but this requirement applies specifically to children born in 2010 or later, unless a valid medical or non-medical exemption is on file. For children born before 2010, varicella is recommended but is not part of the school requirement.

The school requirement for varicella can generally be met either by vaccination or by a documented history of having had chickenpox — your local public health unit can confirm what documentation they accept.

Reporting: As with all vaccines, parents and caregivers are generally responsible for reporting their child's immunizations to their local public health unit, since healthcare providers do not always do this automatically. Make sure each dose is recorded on the immunization record (the "yellow card") and reported — for example, through Immunization Connect Ontario (ICON) if your area uses it.

Second dose as MMRV: In Ontario, the second dose of varicella protection is usually given at 4–6 years as the combined MMRV vaccine, which also includes measles, mumps, and rubella.

Exemptions: If your child cannot receive this vaccine for medical reasons, or you are seeking a non-medical exemption, see the School Requirements hub for the process.

Ingredient Transparency

What's in this vaccine

Two varicella products are used in Canada: Varivax® III (Merck) and Varilrix® (GSK). Either may be used depending on supply. Both are live attenuated vaccines, containing a weakened form of the varicella virus that cannot cause chickenpox in healthy people. The information below reflects their Health Canada product monographs.

Ingredient / Component Category Why it's there Plain-English explanation
Live attenuated varicella-zoster virus (Oka strain) Active ingredient The weakened virus that trains the immune system to recognize varicella. "Attenuated" means weakened. The virus is weakened so it prompts protection without causing chickenpox in healthy people.
Amino acids Stabilizer Help keep the vaccine stable. The building blocks of proteins, found throughout the body and in food.
Sucrose and other sugars/sugar alcohols Stabilizers Protect the vaccine virus and keep the product stable, especially during freeze-drying. Sugars used as stabilizers, similar to those in many foods and medicines.
Gelatin (in some products) Stabilizer / potential allergen Helps protect the vaccine virus. Used as a stabilizer in some live vaccines. Relevant for anyone with a known severe gelatin allergy — mention it to your provider.
Neomycin (trace amounts) Manufacturing process residual (antibiotic) Used during manufacturing to help prevent bacterial contamination. A trace amount may remain; relevant for those with a known severe neomycin allergy.
Water for injection (diluent) Diluent Used to reconstitute the freeze-dried vaccine before injection. Sterile water used to mix the vaccine just before it's given.
About aspirin after vaccination: Because of a rare condition (Reye's syndrome) associated with salicylates and varicella infection, it's recommended to avoid ASA (Aspirin) and salicylate-containing products for a period after varicella vaccination in children and teens. Acetaminophen or ibuprofen can be used instead for discomfort — check with a provider or pharmacist.
Side Effects & Safety

Side effects and safety

Expected / common side effects

  • Soreness, redness, or swelling where the needle was given
  • Mild fever
  • A small number of chickenpox-like spots, near the injection site or elsewhere
  • Fussiness or tiredness

Timing and duration: Because varicella is a live vaccine, some reactions — like a mild fever or a few spots — can appear up to a few weeks after the dose, as the immune system responds. They're usually mild and pass on their own.

About the spots: A small number of vaccinated children develop a few chickenpox-like spots. Rarely, the weakened vaccine virus could theoretically spread from these spots to another person. If your child develops a rash, keeping it covered and avoiding close contact with people who have very weakened immune systems or are pregnant is a sensible precaution — ask your provider if you're unsure.

Home care: Acetaminophen or ibuprofen may be used for discomfort or fever. Avoid ASA (Aspirin) and salicylate-containing products for a period after this vaccine in children and teens (see ingredients note). A cool compress can ease injection-site soreness.

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. Uncommon and usually brief.
  • Spread of vaccine virus — rarely, the weakened vaccine virus can pass from a vaccinated person who develops a rash to a susceptible close contact. This is uncommon and the resulting illness is usually mild.

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

Observation period: Many clinics recommend staying nearby for about 15 minutes after vaccination, as severe allergic reactions — though rare — typically occur shortly after the injection.

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 varicella vaccine, or to any of its components (including neomycin or gelatin)
  • Your child has a weakened immune system — for example, due to certain medical conditions or treatments like chemotherapy or high-dose steroids. As a live vaccine, varicella may not be recommended, or may need specialist input
  • Your child is pregnant (relevant for adolescents) — varicella vaccine is not given during pregnancy
  • Your child has recently received blood products or immune globulin — this can affect how well a live vaccine works, so timing may need adjusting
  • Your child has a moderate or severe acute illness (it's generally fine to wait until they feel better)

These usually do NOT require delaying this vaccine:

  • A mild cold or other minor illness without fever
  • Currently breastfeeding
  • A stable, ongoing chronic health condition
  • Currently taking antibiotics for an unrelated condition
  • A household member who is pregnant or has young children (precautions apply only in the rare case of a post-vaccine rash)
Common Questions

Questions parents often ask

Yes. At the 15-month visit, varicella may be given alongside other scheduled vaccines. As a live vaccine, it has specific timing rules relative to other live vaccines (like MMR) — they're either given together or spaced apart by a minimum interval, which a healthcare provider manages.
Being behind does not mean starting the series over. The remaining doses can generally be given following minimum spacing guidelines. Visit the Catch-Up & Missing Records page, or speak with a healthcare provider to confirm the right plan for your child.
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 child who has had chickenpox is generally considered protected and may not need the vaccine — but confirm this with a healthcare provider, who can review the history. For school, the varicella requirement (for children born 2010 or later) can usually be met either by vaccination or by documented history of the disease; your public health unit can confirm what they accept.
Yes, this can happen. Because it's a live vaccine, a small number of children develop a few chickenpox-like spots, sometimes a week or two after the dose. It's usually mild. Keeping any spots covered and avoiding close contact with people who are pregnant or have very weakened immune systems is a sensible precaution. Contact a provider if your child seems unwell or you're unsure.
This is common and manageable. Gather whatever records you have, and contact your local public health unit or healthcare provider — they can often help locate or reconstruct records, or advise on next steps if records truly cannot be found. See the Catch-Up & Missing Records page.
This vaccine is typically given by a family doctor or nurse practitioner as part of routine infant well-child visits. Some public health units also offer immunization clinics. See the Resources page for links to find services in your area.
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 chickenpox and the vaccine

Fact Chickenpox is usually mild, but it isn't always — it can lead to complications, and because it's extremely contagious, it spreads easily to people who are more vulnerable.
Concern Some parents remember chickenpox as a normal rite of passage and wonder whether it's really necessary to vaccinate against something so common — or whether it's better to let a child catch it ("chickenpox parties").
Evidence While most children recover from chickenpox without issue, a meaningful number develop complications such as serious skin infections, pneumonia, or, less commonly, more severe problems — and it can be dangerous for babies, pregnant people, and those with weakened immune systems. Deliberately exposing a child to the actual disease carries these real risks, whereas the vaccine builds protection without them. Vaccination also reduces the chance of shingles later in life compared with wild infection.
Takeaway "Common" doesn't mean "always harmless." The vaccine provides protection without the risks of the disease, and helps protect more vulnerable people in the community.
Fact Vaccinated children can occasionally still get a mild case of chickenpox, but it's usually much milder than the full disease.
Concern Hearing that a vaccinated child still got chickenpox can make the vaccine seem ineffective.
Evidence No vaccine is 100% effective, and "breakthrough" chickenpox can happen — but it typically involves far fewer spots, less fever, and a quicker recovery. Two doses reduce the chance of breakthrough cases compared with one. Across a population, varicella vaccination has greatly reduced cases and complications.
Takeaway Even when it isn't perfect, the vaccine makes illness much milder and far less likely — which is why two doses are recommended.
Ontario Next Steps

What to do next

Where to get it

Typically given by a family doctor or nurse practitioner during routine well-child visits. Some public health units also offer clinics.

What to bring

Your child's immunization record (the "yellow card"), health card if available, and a list of any allergies or previous reactions.

If you're behind

Catching up does not mean restarting. Visit the Catch-Up & Missing Records page or ask your provider for a review.

If records are missing

Contact your local public health unit — they may have records on file, or can advise on next steps.

If vaccinated outside Ontario

Bring any available records to a healthcare provider for review — products and schedules elsewhere may differ slightly from Ontario's.

Contact public health

For record reporting, school requirements, or general questions, see the Resources page for your local public health unit's contact details.

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.