PAHO Issues Measles Alert as Cases Rise in the Americas

The Pan American Health Organization (PAHO) has issued an epidemiological alert on measles in the Americas, urging countries to strengthen surveillance, expand vaccination, and ensure rapid outbreak response as cases continue to increase across multiple countries in the region.

The alert points to sustained growth in measles cases in 2025 compared with the previous five years, a trend that is continuing into early 2026. PAHO called on health authorities to intensify epidemiological surveillance, including active case finding and laboratory diagnosis, implement supplementary immunization activities to address immunity gaps, and respond quickly to suspected cases to limit transmission.

“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, 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, reports MBN.

In 2025, countries in the Americas reported 14,891 confirmed measles cases and 29 deaths across 13 countries. Mexico recorded 6,428 cases and 24 deaths, while Canada reported 5,436 cases and two deaths. The United States registered 2,242 cases and three deaths. Other countries reporting cases included Bolivia, Paraguay, Belize, Brazil, Uruguay, Argentina, Peru, Costa Rica, El Salvador, and Guatemala. The regional total represents a 32-fold increase compared with 466 cases reported in 2024.

In light of this scenario, last December ​​Mexico’s Ministry of Health deployed a multi-pronged vaccination strategy, administering over 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.

However, during the first three weeks of 2026, an additional 1,031 cases were confirmed in seven countries, with no deaths reported. Mexico accounted for 740 cases in that period, followed by the United States with 171 and Canada with 67. This marks a 43-fold increase compared with the same period in 2025.

Available data show that among confirmed cases with known vaccination status, 78% were unvaccinated and 11% had an unknown status. Although the largest share of cases occurred among adolescents and young adults, the highest incidence rates were observed in infants under one year of age, followed by children aged one to four and five to nine years. PAHO says this pattern highlights the need to complete vaccination schedules and apply additional protective measures during outbreaks.

At the global level, the World Health Organization (WHO) reported over 552,000 suspected measles cases in 179 countries in 2025, of which nearly 45% were confirmed, reflecting continued transmission linked to immunization gaps.

Vaccination coverage in the Americas has improved but remains below the threshold required to prevent outbreaks. Coverage with the first dose of the MMR vaccine rose from 87% in 2023 to 89% in 2024, while second-dose coverage increased from 76% to 79%. However, only 33% of countries and territories achieved at least 95% coverage for the first dose, and 20% reached that level for the second dose. An estimated 1.5 million children in the region did not receive any dose of the vaccine in 2024.

PAHO says that measles is preventable through timely vaccination with two doses of MMR vaccine. In countries with active outbreaks, the organization recommends intensified vaccination, active case detection, and rapid response to interrupt transmission. For all countries, it emphasizes closing coverage gaps, maintaining sensitive surveillance systems, and ensuring that travelers are vaccinated, particularly those going to areas with ongoing transmission.

In the context of the 2026 FIFA World Cup and other mass gatherings associated with high population mobility, PAHO advised countries to increase the sensitivity of surveillance systems through active case finding to promptly detect measles and rubella cases. The organization says it will continue monitoring the situation and update recommendations as needed.

“Organizing large-scale events carries risks regarding the health and safety of all attendees,” says Pascaline Leon, Head of Health, Lifestyle and Beauty, Business France, to MBN.

The increase in cases could challenge Mexico’s health system as the country prepares for the 2026 FIFA World Cup. The event will mark a historic milestone, making Mexico the first country to host the tournament three times, in 1970, 1986, and 2026. President Claudia Sheinbaum states that the event represents a unique opportunity to showcase Mexico’s cultural richness, hospitality, and economic strength on a global stage, reports MBN. Official estimates suggest Mexico will welcome over 5.5 million international visitors, generating between US$1.8 billion and US$3 billion in economic impact.