A dramatic rise in measles cases across North America and Europe has led top immunologists to declare a “post-herd-immunity world,” as vaccination rates decline and preventable diseases resurface with deadly consequences. Dr. Paul Offit, a leading U.S. vaccine expert, warned that the resurgence of measles—the most contagious human disease—shows the erosion of public health protections once thought secure.

The U.S. is facing its largest measles outbreak in 25 years, with over 935 cases across 30 states. The epicenter in west Texas has seen fatalities, including two unvaccinated children. Neighboring states like New Mexico and Oklahoma are also reporting rising infections. Nearly a third of infected children under five have required hospitalization.

In the broader Americas region, Canada and Mexico are also grappling with outbreaks. These three countries now account for the majority of the World Health Organization’s 2,300 reported cases in the region, an eleven-fold increase from the previous year.

Much of the spread has occurred in communities with low vaccination rates, including Mennonite populations with limited public health outreach. While not opposed to vaccines on religious grounds, barriers such as language, isolation, and misinformation have left these communities vulnerable.

In Europe, cases have surged tenfold, with Romania accounting for the vast majority of the 35,000 cases reported in 2024. Health authorities cite declining vaccine coverage as the main driver, with only three countries reaching the 95% threshold needed for herd immunity.

Medical organizations continue to stress that there is no cure for measles, and prevention through the MMR vaccine—which is 97% effective—remains the only safe and proven defense. The disease kills approximately 1 in 1,000 infected children and often causes severe complications such as encephalitis.

Global health leaders emphasize that the loss of herd immunity endangers entire populations and reverses decades of progress. Measles vaccination alone is credited with saving over 93 million lives worldwide since 1974.