Americas’ Measles-free Status in Jeopardy Due to Ongoing Transmissions

Continued measles spread in Canada, Mexico, and the United States has put these countries at risk of losing measles-free status, the head of the Pan American Health Organization (PAHO), the Americas arm of the World Health Organization (WHO), told Reuters.

A country where an outbreak takes place must get back to zero cases within 12 months to be considered measles-free. That deadline expires at the end of October for Canada, while the U.S. has until January and Mexico until February.

The outbreaks are linked primarily to low vaccination coverage, with 71% of cases in the Americas occurring in unvaccinated individuals and another 18% in people whose vaccination status is unknown. In 2024, coverage with the first dose of the measles, mumps, and rubella (MMR) vaccine in the region reached 89% (two percentage points higher than in 2023), while the second dose increased from 76% to 79%.

PAHO said 95% of a population needs to be vaccinated to prevent the spread of measles. As of Aug. 8, a total of 10,139 confirmed measles cases and 18 related deaths have been reported across ten countries in the Americas, representing a 34-fold increase compared to the same period in 2024.

“Studies have shown that exposure to vaccine misinformation, even for a short period of time, can negatively influence people’s perceptions and their decision to get vaccinated,” said Daniel Salas, PAHO executive manager of the Special Program for Comprehensive Immunization. “Even individuals who have been vaccinated in the past can be negatively influenced by misinformation.”

Canada leads the Americas in measles cases in 2025. According to WHO data, 92% of the population in Canada has had the first dose of vaccine, and only 79% the second dose, which is needed for full protection. More than 5,000 measles cases have been reported in Canada this year as of Oct. 6 along with two deaths, including a newborn baby in Alberta last week. 

The U.S. and Mexico have also had significant measles outbreaks this year. As of Sept. 30, the Centers for Disease Control and Prevention has confirmed 1,544 measles cases in the U.S. along with three death from the disease. As of Sept. 10, WHO has confirmed 4,000 cases in Mexico, and PAHO has confirmed 14 deaths in the country as of Aug. 8.