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The Pan American Health Organization (PAHO) issued a new epidemiological alert on Wednesday following a surge in measles cases across the Americas, with Mexico recording the highest numbers. The urgent warning comes as health authorities grapple with a dramatic increase in infections, raising concerns about the region’s measles elimination status and vaccination coverage gaps.
According to the organization, 1,031 new measles cases were confirmed in seven countries during the first three weeks of 2025, representing a staggering 43-fold increase compared to the same period last year. Mexico leads with 740 cases, followed by the United States with 171 cases and Canada with 67 cases, though no deaths have been reported thus far.
Vaccination Gaps Drive Measles Outbreak
PAHO emphasized that 78 percent of recent cases involved individuals who had not received vaccination against the highly contagious disease. The organization has called for urgent immunization campaigns to close immunity gaps and prevent further transmission. Measles remains one of the most infectious viral diseases, spreading rapidly in populations with inadequate vaccine coverage.
The alert follows Canada’s loss of its measles-free status in November, a significant setback for public health efforts in the region. Both the United States and Mexico may soon face similar downgrades if current outbreaks are not brought under control quickly.
Regional Elimination Status Under Threat
Meanwhile, both the U.S. and Mexican governments have requested a two-month extension to manage the disease outbreaks within their borders. The requests highlight the challenges authorities face in containing the virus amid declining vaccination rates and increased population movement across the Americas.
However, the situation is complicated by the Trump administration’s withdrawal from the World Health Organization in January. WHO serves as the parent organization to PAHO, and the U.S. exit has raised questions about future cooperation and funding for regional health initiatives targeting measles and other vaccine-preventable diseases.
Understanding the Measles Resurgence in the Americas
Public health experts attribute the resurgence to multiple factors, including vaccine hesitancy, disrupted immunization programs, and pockets of unvaccinated populations. The measles vaccine is highly effective, with two doses providing approximately 97 percent protection, according to health authorities. Additionally, the virus can linger in the air for up to two hours after an infected person leaves a room, making prevention through vaccination critical.
In contrast to previous years when the Americas maintained high immunization coverage, recent trends show declining vaccination rates in several countries. This has created vulnerable populations where measles can spread quickly, particularly among children and young adults who missed routine childhood vaccinations.
Broader Implications for Regional Health Security
The epidemiological alert underscores broader concerns about public health infrastructure and disease surveillance across the hemisphere. PAHO’s warning serves as a reminder that measles elimination requires sustained effort and high vaccination coverage of at least 95 percent in all communities.
Furthermore, the outbreak demonstrates how quickly progress can be reversed when immunization programs falter. The Americas region was declared free of endemic measles in 2016, making the current situation particularly troubling for health officials working to maintain that achievement.
Health authorities have not confirmed whether the two-month extension requested by the United States and Mexico will be sufficient to regain control of the outbreaks. The coming weeks will be critical in determining whether additional countries lose their measles-free status and whether vaccination campaigns can successfully halt transmission chains before the virus becomes re-established in the region.
