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Adverse Events Following Immunization (AEFI)

  • Serious side effects from vaccines are rare.
  • Many negative events can be avoided through proper administration of vaccines and assessing patients for contraindications prior to immunization.
  • Physicians, members of the College of Nurses of Ontario, and members of the Ontario College of Pharmacists must report AEFI to their Medical Officer of Health under Section 38 of the Health Protection and Promotion Act (HPPA).
  • For the safe monitoring of vaccines, it is important to report any adverse effects after an immunization.  The Adverse Events Following Immunization report form should be completed and submitted to the Health Unit within seven days of a suspected reaction to distinguish true vaccine reactions from coincidental, unrelated events.

AEFI Fact Sheet

Invasive Meningococcal Disease

Invasive meningococcal disease (IMD) is a serious infection caused by the bacteria, Neisseria meningitidis. Up to 10% of the population carry the bacteria at the back of their throat or nose without ever getting sick. In rare cases, IMD can cause an infection of the lining of the brain and spinal cord (meningitis) and/or an infection of the bloodstream (septicemia).

Care for your Child after Vaccinations

Vaccines, like any medicine, can have side effects that are usually mild and brief. Most children are fine after getting a shot. Side effects are usually minimal and last less than 24 hours. In rare cases, a child may have a serious allergic reaction. The risks of a serious reaction happening are lower than the risks of the diseases the shots prevent. After your child receives a vaccination (shot), your child will be asked to wait for 15 minutes to make sure that there are no side effects.