An oral (liquid) vaccine that protects against rotavirus (Rotarix®)
An oral (liquid) vaccine — given by mouth, not as an injection.
Rotavirus is a very common virus that causes gastroenteritis — inflammation of the stomach and intestines — in infants and young children.
| Disease | What parents might notice | How it spreads | Why it can be serious | How vaccination helps |
|---|---|---|---|---|
| Rotavirus gastroenteritis | Watery diarrhea, vomiting, fever, and tummy pain — sometimes lasting several days. | Very easily, through contact with tiny amounts of stool from an infected person — for example, on hands, toys, or surfaces. It spreads readily in households and childcare settings. | The biggest risk is dehydration from fluid loss, which in young infants can become serious quickly and sometimes requires hospital care for rehydration. | The vaccine greatly reduces the chance of severe rotavirus illness and the dehydration and hospital visits that can come with it. |
Why so early? Rotavirus illness is most dangerous for young infants, so the vaccine is given early — at 2 and 4 months — to build protection before a baby is likely to be exposed.
Why the age limits matter. Rotavirus vaccine is one of the few with firm age limits. Based on current Canadian guidance, the first dose should be given starting at 6 weeks and before 15 weeks of age, with doses at least 4 weeks apart, and the series should be completed by 8 months of age. These limits exist because the vaccine hasn't been well studied when started in older infants and because of a rare risk consideration (see safety section). If your baby is approaching these age limits, or has missed a dose, contact your healthcare provider or local public health unit promptly.
What if a dose is late or missed? Because of the age limits, a missed rotavirus dose sometimes cannot be made up — unlike most other vaccines. If you think you may be running close to the age cutoffs, contact your healthcare provider promptly. See the Catch-Up & Missing Records page for general guidance.
Can it be given with other vaccines? Yes. It's routinely given at the same 2 and 4-month visits as the 5-in-1 and pneumococcal vaccines. Because rotavirus vaccine is taken by mouth, it doesn't add another needle to the visit.
So while rotavirus vaccine is strongly recommended for the protection it offers babies, rotavirus is not an ISPA-designated disease for school attendance, and missing it does not trigger the ISPA suspension process.
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 your child's immunization record (the "yellow card") and reported — for example, through Immunization Connect Ontario (ICON) if your area uses it.
The product used in Ontario is Rotarix® (GSK), based on its Health Canada product monograph. It's a live, attenuated (weakened) vaccine given by mouth. It comes as a ready-to-use liquid.
| Ingredient / Component | Category | Why it's there | Plain-English explanation |
|---|---|---|---|
| Live attenuated human rotavirus (strain RIX4414) | Active ingredient | The weakened virus that trains the immune system to recognize rotavirus. | "Attenuated" means weakened. The virus is weakened so it prompts an immune response without causing the illness it protects against. |
| Sucrose | Stabilizer | Helps protect and stabilize the vaccine. | A sugar used as a stabilizer. (The amount is too small to be a concern for rare sugar-related metabolic conditions, per the manufacturer.) |
| Dextran | Stabilizer | Helps keep the vaccine stable. | A complex sugar used as a stabilizer in some medical products. |
| Sorbitol | Stabilizer | Helps keep the vaccine stable. | A sugar alcohol used as a stabilizer in many foods and medicines. |
| Amino acids and cell-culture medium (DMEM) | Manufacturing components | Support the growth of the vaccine virus. | Amino acids are the building blocks of proteins. DMEM is a nutrient mixture used to grow the virus during manufacturing. |
| Calcium carbonate (in the formulation) | Antacid component | Protects the vaccine from stomach acid so it can work. | An antacid (the same kind of compound found in some indigestion remedies) that shields the vaccine as it passes through the stomach. |
| Sterile water | Base | The liquid base of the oral vaccine. | Sterile water that makes up the liquid. |
Expected / common side effects
Timing and duration: Any mild tummy symptoms usually occur in the days after a dose and tend to be short-lived.
Home care: Keep your baby comfortable and well-hydrated with their usual feeds (breastmilk or formula). There are no food or feeding restrictions around the vaccine. If you're worried about dehydration — far fewer wet diapers, unusual drowsiness, no tears when crying — contact a healthcare provider.
Is the live virus contagious? The weakened vaccine virus can be present in a baby's stool for a short time after the dose. Normal hand-washing — especially after diaper changes — is enough to manage this. Let a healthcare provider know if anyone in close contact has a seriously weakened immune system.
Many babies have no side effects at all, and that does not mean the vaccine didn't work.
Rare but important
About intussusception: This is uncommon, but it's worth knowing the signs, especially in the week or so after a dose. Watch for: episodes of severe tummy pain (a baby may cry and pull their knees up), repeated vomiting, blood or a "red-currant-jelly" appearance in the stool, or a baby who is unusually weak, floppy, or very drowsy.
If you see these signs, seek medical care right away — go to an emergency department or call 911. Intussusception can be treated, and getting care quickly matters.
The age limits on the schedule exist partly to keep this rare risk as low as possible. Overall, the benefits of protecting against severe rotavirus illness are considered to outweigh this small risk — but being aware of the signs is sensible.
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
Given by mouth by a family doctor or nurse practitioner during routine 2 and 4-month well-child visits. Some public health units also offer clinics.
Watch the timing
Because of the age limits, try to book the 2-month visit on time. If your baby is nearing 15 weeks without a first dose, contact your provider or local public health unit promptly.
What to bring
Your baby's immunization record (the "yellow card") and a note of any tummy or immune-system conditions or family history of intussusception.
Know the warning signs
Familiarize yourself with the signs of intussusception (above) so you can act quickly in the rare event they appear after a dose.
If vaccinated outside Ontario
Bring any records to a provider — a different rotavirus product (such as a 3-dose schedule) may have been used elsewhere.
Report the doses
Make sure each dose is recorded and reported to your public health unit. See the Resources page.
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.