The year 2025 has witnessed a troubling resurgence of one of the most contagious viral infections measles. Health authorities across Canada and the United States have confirmed that each country has now crossed 1,000 reported cases, marking the deadliest measles outbreak in over three decades.

As of May 8, 2025, 31 jurisdictions, led by the state of Texas, reported 1,001 confirmed measles cases. The United States is on track to exceed the 1,279 cases reported in 2019, when an unvaccinated religious group led to cases in several cities, including New York.

To notify international travellers of this health risk, the CDC reissued a Travel Health Advisory in March 2025, identifying 57 countries reporting measles cases. The CDC writes, ‘All international travellers should be fully vaccinated against measles with the measles-mumps-rubella vaccine, including an early dose for infants.’

As of May 11, 2025, the CDC has not included Texas, Ontario, Canada, or Mexico (700+) in its measles advisory.