The US and Mexico are on the verge of forfeiting a major health victory. Here's what to know

This week, international health experts are convening to determine if the United States and Mexico have forfeited their major achievement in eliminating measles. For over 30 years, vaccines had successfully stopped the spread of the virus, making measles a rare occurrence in the U.S., with nearly zero deaths. However, in the past two years, large outbreaks have hit multiple states, resulting in thousands of illnesses and about a dozen deaths.

Experts expect the Pan American Health Organization (PAHO) meeting to show that measles has officially returned to the U.S. and Mexico, indicating the virus is now continually spreading within the countries' borders. Dr. David Margolius, director of Cleveland's health department and a leader, explains that the decision represents a significant setback.

The PAHO advisory commission is examining genetic evidence to determine if the same measles virus has been circulating for one year or more in the ongoing outbreaks in North America, starting in 2024. If it is confirmed, the commission will declare the countries no longer eligible for the "eliminated" designation, signifying a return to the constant circulation of the virus.

Last year, PAHO removed Canada from the measles-free list it had maintained since 1998. The commission's determination will be presented to PAHO Director Dr. Jarbas Barbosa, who makes the final decision. The CDC, however, maintains that losing the measles elimination status will not alter its approach to addressing outbreaks. CDC Director Erica Schwartz stresses that vaccination remains the primary protection against measles and that the decision does not signify a shift away from evidence-based strategies.