Measles cases are surging across the Americas, with a particularly concerning rise in Mexico and the United States. As of , the Centers for Disease Control and Prevention (CDC) has reported confirmed measles cases in the U.S. For 2026, with the vast majority – – occurring in states. An additional cases were identified in international visitors to the U.S.
The situation in Mexico is significantly more severe. According to data released by the Secretaría de Salud, as of , Mexico has confirmed measles cases and deaths across all states and municipalities. This represents a substantial increase in cases over the past year, with cases reported over the last 12 months and deaths confirmed.
The Pan American Health Organization (PAHO) has issued an alert, noting a -fold increase in measles cases across seven countries in the first three weeks of compared to the same period last year. Mexico currently leads with cases, followed by the United States with and Canada with .
Within Mexico, Chihuahua is the most affected state, accounting for of the confirmed cases. Jalisco follows with cases, and Chiapas has reported . The majority of deaths have also occurred in Chihuahua, with fatalities reported in . Additional deaths have been reported in Jalisco (), Sinaloa (), Durango (), Michoacán (), and Tlaxcala ().
The most vulnerable age groups appear to be young children. In Mexico, the highest number of cases are occurring in children aged to years old ( cases), followed by those aged to years old ( cases), and to years old ( cases).
Measles is a highly contagious viral illness that can cause fever, cough, and a characteristic rash. It is so contagious that, according to experts, each infected person can infect an average of to susceptible individuals. Up to % of unvaccinated individuals will contract the disease if exposed.
Fortunately, the measles vaccine is highly effective. A single dose protects % of individuals, and two doses increase protection to %. For most people, this protection is lifelong. When % to % of the population is immune, either through vaccination or prior infection, the virus struggles to spread, achieving what is known as herd immunity.
The current outbreaks are largely driven by sustained transmission in under-immunized communities. In the U.S., % of confirmed cases are outbreak-associated, meaning they are linked to ongoing outbreaks that began in or . In Mexico, over % of confirmed cases are among individuals with no history of vaccination, and severe cases and deaths are concentrated in those with incomplete vaccination schedules, young children, and individuals with weakened immune systems.
While cases in vaccinated individuals are rare and generally mild, they are likely to become more common as exposure to the virus increases. The resurgence of measles underscores the critical importance of maintaining high vaccination rates to protect both individuals and communities.
