Public health officials in Ontario are urging parents to make sure their children are fully immunized against measles as the province continues to battle an outbreak that has already infected more than 2,300 people since October 2024.
Public Health Ontario (PHO) says children and teens remain the most affected group, representing over 73 per cent of reported cases. Alarmingly, 96 per cent of those were not vaccinated. “The current measles outbreak has highlighted how important it is for all Ontarians to be up to date with their measles vaccinations,” PHO said in a statement.
Ontario’s standard immunization schedule calls for two doses of measles protection: the first at age one as part of the measles, mumps and rubella (MMR) vaccine, and the second between four and six years of age as part of the MMRV vaccine. But with some children entering school before their fourth birthday, parents are asking whether an early second dose is possible.
According to PHO, the answer is yes in some areas. “In public health units where the outbreak vaccine strategy is in place, parents and guardians of children under four years can speak with their health-care providers about receiving an early second dose in advance of the school year,” the agency confirmed.
Unvaccinated individuals remain at the greatest risk of contracting measles, with infants, pregnant people and those with compromised immune systems facing the most severe complications. The virus, which spreads easily through coughing, sneezing or contaminated air and surfaces, can linger for up to two hours and often leads to serious illnesses such as pneumonia, ear infections, and in rare cases, brain swelling or death.
The ongoing outbreak also threatens Canada’s measles elimination status, which has been recognized since 1998. The Public Health Agency of Canada warns that if community transmission of the same strain continues beyond Oct. 27, the country could lose that designation.
Officials say the outbreak began with international travel but has since spread largely within Canada, particularly in undervaccinated communities. They emphasize that maintaining high vaccination rates is the best defence.
For parents, the message is clear: make sure children are up to date on their shots — and ask a health provider about early vaccination if school is starting before age four.