Human papillomavirus vaccine (Gardasil®9) — offered through Ontario's Grade 7 school program
Protects against the human papillomavirus, which is linked to several cancers later in life.
HPV (human papillomavirus) is a very common virus. Most people will be exposed to it at some point, and in many cases the body clears it on its own. But some types can lead to cancer or other diseases years later. The vaccine protects against nine of the highest-risk and most common types.
| What HPV can cause | What it involves | How it spreads | Why it can be serious | How vaccination helps |
|---|---|---|---|---|
| Cervical cancer | Cancer of the cervix, often developing years or decades after HPV infection. | HPV spreads through intimate skin-to-skin contact. | Certain HPV types cause the large majority of cervical cancers. | The vaccine protects against the HPV types responsible for most cervical cancers, ideally before any exposure. |
| Other cancers | HPV is also linked to cancers of the anus, penis, vulva, vagina, and throat/mouth (oropharyngeal). | Intimate skin-to-skin contact. | These cancers can affect people of any gender, which is why the vaccine is offered to all children, not only girls. | By preventing infection with high-risk HPV types, the vaccine reduces the risk of these cancers later in life. |
| Genital warts | Warts in the genital area, caused by certain lower-risk HPV types. | Intimate skin-to-skin contact. | Not cancerous, but can cause distress and require treatment. | Gardasil 9 includes protection against the two HPV types that cause most genital warts. |
Why Grade 7 / early adolescence? The HPV vaccine works best when given before any exposure to the virus. Since HPV spreads through intimate contact, vaccinating in early adolescence — well before most people become sexually active — provides the strongest protection. It's not about expecting any particular behaviour; it's about building protection well in advance, the way you'd put on a seatbelt before driving rather than during a crash.
Why two doses? When the series is started between ages 9 and 14, the immune system responds especially well, and two doses (at least 6 months apart) provide strong protection. People who start the series at 15 or older, or who have certain immune conditions, may need three doses. A healthcare provider or public health unit can confirm the right number for an individual.
What if a dose is late? If the second dose is delayed, the series does not need to restart — the next dose can be given when possible. If the two doses end up given less than 6 months apart, a third dose may be recommended. See the Catch-Up & Missing Records page, or ask your public health unit.
Can it be given with other vaccines? Yes. In Grade 7, HPV is offered alongside the meningococcal ACYW and hepatitis B vaccines through the school program. These may be given at the same visit, at different injection sites.
This distinction is a common source of confusion, because the HPV vaccine is offered at school alongside the meningococcal ACYW vaccine — and meningococcal disease is ISPA-required. It's easy to assume everything offered in the school clinic carries the same requirement, but they don't. HPV (and hepatitis B) are publicly funded, school-based, and recommended, but participation is a choice rather than a school-attendance requirement.
What "school-based" means here: Public health nurses typically visit schools to offer these vaccines, which makes them convenient and accessible. Parents and caregivers are asked to provide consent. If your child misses the school clinic, the vaccine remains free through your local public health unit (through Grade 12), and sometimes through other providers.
Reporting: When the vaccine is given through a school-based clinic run by public health, the public health unit usually records it directly. If your child receives HPV vaccine elsewhere, you may need to report it to your local public health unit yourself.
The HPV vaccine used in Ontario's program is Gardasil®9 (Merck). The information below is based on its Health Canada product monograph. Gardasil 9 is not a live vaccine and does not contain any virus — it uses lab-made proteins that mimic the outer shell of the virus.
| Ingredient / Component | Category | Why it's there | Plain-English explanation |
|---|---|---|---|
| HPV L1 proteins (types 6, 11, 16, 18, 31, 33, 45, 52, 58) | Active ingredients | These are the parts that train the immune system to recognize HPV. | These are purified proteins that self-assemble into "virus-like particles" — empty shells that look like the outside of HPV to the immune system, but contain no genetic material and cannot cause infection. |
| Amorphous aluminum hydroxyphosphate sulfate (AAHS) | Adjuvant | Helps the immune system respond more strongly and produce longer-lasting protection. | An aluminum-based adjuvant. Aluminum salts have been used safely in vaccines for decades, in small amounts. This is discussed further in the "What the evidence shows" section. |
| Yeast protein (trace amounts) | Manufacturing process residual / potential allergen | The HPV proteins are grown using baker's yeast (Saccharomyces cerevisiae), so trace amounts of yeast protein may remain. | This is relevant for anyone with a known severe yeast allergy — discuss it with a healthcare provider if it applies to your child. |
| Polysorbate 80 | Stabilizer / potential allergen | Helps keep the vaccine's ingredients evenly mixed and stable. | A common ingredient in many foods, cosmetics, and medications. Listed as a potential allergen in the product monograph, though severe reactions to it are rare. |
| L-histidine | Buffer | Helps keep the vaccine at a stable acidity (pH). | An amino acid (a building block of protein) that the body uses normally and that helps keep the vaccine stable. |
| Sodium borate | Buffer | Helps maintain the vaccine's stability and acidity. | Used in very small amounts as a buffering agent to keep the product stable. |
| Sodium chloride | Tonicity agent | Helps match the vaccine's salt concentration to that of the body. | Ordinary salt, used so the injection is gentler on the body's tissues. |
| Water for injection | Base | The liquid base of the vaccine. | Sterile water that makes up most of the injection's volume. |
Expected / common side effects
Timing and duration: These reactions usually appear within a day or so and typically resolve within 1–2 days.
Fainting: Fainting can happen after any vaccine in adolescents, and is more about the experience of being vaccinated than the vaccine itself. Because of this, the person giving the vaccine may ask your child to sit or stay nearby for about 15 minutes afterward. Let the clinic know if your child has fainted with needles before.
Home care: A cool compress can help with injection-site soreness. Acetaminophen or ibuprofen may be used as directed for discomfort or fever. People under 19 should not be given ASA (Aspirin) or salicylate-containing products.
Mild side effects can happen as the immune system responds. Many people have no side effects at all, and that does not mean the vaccine didn't work.
Rare but important
What clinics do to reduce risk: Clinics ask about allergy history before vaccination, are equipped with epinephrine and trained staff, and have your child sit during and after the injection to reduce the chance of injury from fainting.
Observation period: Staying seated and nearby for about 15 minutes after the vaccine is recommended, which addresses both rare severe allergic reactions and the more common possibility of fainting.
A note on safety monitoring: HPV vaccines have been used for over 15 years and have been studied extensively in millions of people. They continue to be monitored for safety.
Get urgent help now if your child has:
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.
Speak with a healthcare provider before this vaccine if:
These usually do NOT require delaying this vaccine:
Where to get it
Offered free through Grade 7 school clinics run by your local public health unit. Also available free through the public health unit (through Grade 12).
What to bring / do
Watch for the consent form sent home through school, and return it on time. Note any allergies or a history of fainting with needles.
If you missed the school clinic
Contact your local public health unit to arrange a free dose. Catch-up is funded through Grade 12.
If records are missing
Your public health unit usually records school-clinic doses directly. Contact them to confirm what's on file.
If vaccinated outside Ontario
Bring any records to a healthcare provider or public health unit so the series can be reviewed and continued if needed.
Contact public health
For consent questions, scheduling, or to report a dose given elsewhere, see the Resources page for your local public health unit.
This page is based on:
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.