You probably remember hearing that measles was supposed to be gone.
For decades the shot given to toddlers was the quiet reason you did not know anyone who had it. That is no longer a safe assumption.
A yearlong outbreak in Canada ended with the country losing the measles-free status it had held since 1998. The same virus strain was later picked up in other Canadian provinces, the United States, Mexico and the Netherlands.
The analysis, published October 12, 2026 in The BMJ, traced 2,377 cases across Ontario from late October 2024 to early October 2025. Nearly 9 in 10 patients were unvaccinated.
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Most cases happened inside historically undervaccinated communities with tight social ties. Roughly three quarters of patients were 19 years old or younger.
The virus did not stay in one country
The researchers linked the cross-border pattern to close social networks between undervaccinated communities on different sides of the border, combined with how easily measles spreads.
US pockets of low vaccination are already being hit hard.
The CDC has logged 4,588 confirmed measles cases in 2026 as of October 22. Cases have been reported in 47 jurisdictions, including California, New York, Texas, Florida and Pennsylvania.
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Three people in the US have died from measles so far in 2026. Among confirmed cases, 89 percent were unvaccinated or had an unknown vaccination history.
Kindergarten MMR coverage in the US has slipped to 92.4 percent, down from 95.2 percent before the pandemic. The CDC links the national surge partly to that decline.
What the Canadian outbreak actually cost
The outbreak sent 166 people to hospital and 13 to intensive care. Fifty-one pregnant women caught measles. Ten babies were born with congenital measles. One patient developed encephalitis, meaning swelling of the brain. One infant died.
Canada formally lost its measles elimination status in November 2025.
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According to CIDRAP at the University of Minnesota, the status can only be regained after 12 consecutive months without transmission from the outbreak strain.
What families can do before the next trip or visit
Two doses of the MMR vaccine remain the main way to prevent measles. Adults who are unsure of their vaccination status, especially before travel or a visit to a newborn, can ask their doctor about getting checked.
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This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.