Ontario health officials have declared the province’s prolonged measles outbreak officially over after nearly a year of transmission that infected more than 2,300 people and tragically claimed the life of a newborn. Public Health Ontario confirmed Thursday that the outbreak ended on Monday, marking 46 days since the last reported case — twice the maximum incubation period for the virus.
Dr. Kieran Moore, Ontario’s chief medical officer of health, announced that the final confirmed case developed a rash on August 21, 2025. “We have now surpassed the required threshold with no additional cases identified,” Moore said, calling the moment an important milestone for the province. The outbreak began in October 2024 after exposure linked to a traveler from New Brunswick, which declared its own outbreak over in January. In Ontario, the infection spread through 26 local health units, affecting a total of 2,375 people.
Nearly three-quarters of those infected were infants, children, or adolescents, and over 96 percent were unvaccinated. During the outbreak, a baby in southwestern Ontario who was exposed to measles in the womb died after being born prematurely to an unvaccinated mother. Alberta, which remains in the midst of its own measles outbreak with nearly 1,925 reported cases, reported a similar infant death earlier this month.
Canada, which declared measles eliminated in 1998, faces the possibility of losing that status later this month. The World Health Organization revokes elimination status if a country experiences 12 months of continuous transmission. Ontario’s outbreak lasted just short of that threshold, but outbreaks continue to appear in nearly every province, according to the Public Health Agency of Canada. Only Yukon and Nunavut have reported no cases this year.
Dr. Moore cautioned that while the end of the outbreak represents significant progress, measles remains a serious and highly contagious disease. He urged parents and guardians to ensure their children’s vaccinations are up to date. “Two doses of the MMR vaccine offer nearly 100 per cent protection and have been safely used for decades,” he said. Health officials added that continued vigilance is essential to prevent the return of widespread measles transmission across Canada.
