Vaccines must pass many safety tests before they are approved and effective for people in preventing the disease that they target.
Vaccines are among the most strictly regulated medical products in Canada. Every single vaccine is tested according to strict guidelines for safety and quality before it is used.
***PHAC ‘’Vaccine Safety in Canada’’ poster: vaccine-safety-poster-eng.pdf (canada.ca)***
As with any medical procedure, immunization has some risks. Individuals may react differently to vaccines. When considering immunization, both the risks and the benefits should be discussed with a qualified health care provider. The risks of vaccine preventable diseases are many times greater than the risks of a serious vaccine side effect.
Most children tolerate vaccines well but it's common to have temporary side effects. These usually last from a few hours to a few days after vaccination and go away on their own.
This is the body's natural response, as it's working to build immunity against the disease. Most side effects don't disrupt daily activities.
Common vaccine side effects may include:
Like any medicine or treatment, side effects can occur after vaccination. Most side effects are minor and don’t last very long.
Some known rare events include anaphylaxis (a severe allergic reaction) which can occur in about one in every one million doses of vaccine given. It usually happens shortly after a person receives the vaccine and is treatable.
Your health care provider is prepared to treat any reaction if it should happen. This is why staying at the clinic for 15 minutes after getting any vaccine is important so they can watch for abnormal or very rare reactions and treat them quickly. Vaccination sites have a supply of epinephrine to use in case you have an allergic reaction.
Signs and symptoms of anaphylaxis may include:
If you experience any of these symptoms at the vaccination site, report it to your health care provider.
Call emergency services right away if you have left the vaccination site and develop any serious symptoms that could be an allergic reaction.
Stress-related reactions, including pain, fear and fainting, are potential side effects of vaccination. They can make people uncomfortable or afraid of vaccinations, which can be a barrier to future vaccination.
A small number of people who are very anxious about vaccines may:
These symptoms can lead to fainting during or shortly after receiving a vaccine. Fainting is usually triggered by pain or anxiety. Sometimes when people faint, their bodies make jerking movements. These movements can sometimes be confused with seizures but are not actual seizures. Fainting itself is generally not serious, but harm can occur from related falls.
People may remain pale and sweaty for several minutes afterwards.
Let a health care provider know if you have a fear of needles or a history of fainting before, during or after. You may be able to receive your vaccine lying down. This way health care providers can prepare for and manage these side effects.