Growing Number of Measles Cases Put the Americas at Risk

Global immunization efforts have reduced measles deaths by 88% between 2000 and 2024, saving nearly 59 million lives, yet cases surged worldwide in 2024, reaching an estimated 11 million infections, according to the World Health Organization (WHO). The Americas, which achieved a historic return to measles elimination with a 98% drop in cases in 2024, now faces renewed transmission in 2025, exposing vulnerabilities in immunization coverage.

“Measles is the world's most contagious virus, and these data show once again how it will exploit any gap in our collective defenses against it,” says Tedros Adhanom, Director General, WHO. “Measles does not respect borders, but when every child in every community is vaccinated against it, costly outbreaks can be avoided, lives can be saved, and this disease can be eliminated from entire nations.”

The Americas had previously reduced estimated cases from 116,365 in 2019 to just 2,320 in 2024, and measles deaths fell to essentially zero. This achievement allowed the region to be reverified for measles elimination in 2024, becoming the only WHO region to regain elimination status after Venezuela’s re-verification in 2023 and Brazil’s in 2024.

However, the success proved fragile. First-dose measles vaccination coverage in the Americas recovered to 88% in 2024 — above the global average of 84% — but remained below the 95% needed at national and subnational levels to prevent outbreaks and sustain elimination. Pockets of under-vaccinated communities, combined with imported cases, have resulted in outbreaks in several countries in 2025, including Canada and Mexico, leading to sustained transmission and the loss of the region’s measles-free status as of November 2025.

In 2024, WHO estimates that 84% of children in the Americas received their first dose of the measles vaccine, while only 76% received the second. Globally, over 30 million children remained under-protected against measles, three-quarters of them in Africa and the Eastern Mediterranean, often in conflict-affected or vulnerable settings. The Immunization Agenda 2030 (IA2030) Mid-Term Review highlights that measles is often the first disease to resurge when vaccination coverage drops, exposing weaknesses in health systems and threatening progress toward elimination goals.

Mexico has confirmed over 5,000 cases nationwide, with children under five years old representing the largest affected group. Chihuahua has been the epicenter, accounting for more than 95% of cases and most fatalities. Smaller outbreaks have been reported in Guerrero, Jalisco, State of Mexico, Michoacan, Queretaro, Sinaloa, and Mexico City. As of late November 2025, national coverage for the two-dose measles schedule stands at 81.1%, with six-year-old coverage rising to 92%, though gaps remain, particularly among children who missed routine immunizations during the COVID-19 pandemic. Over 340,000 children in Mexico did not receive any routine vaccines in 2024.

To address this problem, Mexico’s Ministry of Health has deployed a multi-pronged vaccination strategy, administering more than 8.8 million doses of measles-mumps-rubella (MMR) and measles-rubella (MR) vaccines. Authorities also acquired nearly 6 million additional doses. Vaccination campaigns have expanded eligibility to children as young as six months, adolescents, adults up to 49 years old, seasonal agricultural workers, teachers, and health personnel. House-to-house visits, mobile brigades, and vaccination perimeters covering 25 city blocks around confirmed cases have been established to contain the spread.

“The only way to control measles is through vaccination. Families should review immunization records and complete pending schedules. Vaccination is an act of love,” says Mexico’s Minister of Health, David Kershenobich.

The federal government also launched a 079 phone line in Mexico City to direct residents to vaccination sites and reinstituted National Vaccination Weeks and the National Public Health Week to reinforce immunization. Outreach campaigns utilize community radio, indigenous-language materials, schools, and workplaces.

PAHO is providing technical assistance across the region to strengthen epidemiological surveillance, improve laboratory testing, expand vaccination campaigns, and monitor high-risk areas. Specialists stress that sustained coverage of at least 95% with two doses is required to halt transmission and maintain elimination status.

“We must restore the use of existing vaccines to prevent resurgences of diseases we previously thought were under control, like measles,” says Rodrigo Romero, Coordinator, Mexican Association of Vaccinology. 

Globally, measles cases rose by 86% in the WHO Eastern Mediterranean Region, 47% in the European Union, and 42% in South-East Asia between 2019 and 2024. The African Region saw a 40% decline in cases and a 50% decline in deaths during the same period, partly due to improved immunization coverage. In 2024, 59 countries reported large or disruptive measles outbreaks, nearly triple the number in 2021, highlighting the consequences of underfunded immunization programs and weakened health systems.

The Americas’ loss of measles-free status underscores the fragility of prior gains and the importance of political commitment, regional cooperation, and sustained investment in vaccination, surveillance, and outbreak response. Previous temporary setbacks in Venezuela and Brazil were reversed through coordinated campaigns, demonstrating that elimination can be regained if sustained transmission is interrupted.