US Measles Cases Surge to Highest Level in 35 Years Amidst Vaccination Decline and Data Disputes

The United States has recorded a staggering 5,182 confirmed cases of measles in 2026, marking the highest tally since 1991, according to the latest data from the Centers for Disease Control and Prevention (CDC). This highly contagious yet vaccine-preventable disease disproportionately affects the young, with children under five accounting for 18 percent of cases and those aged five to 19 making up an additional 41 percent. In total, children and teenagers represent approximately 59 percent of all confirmed infections.

The vast majority of these cases, 4,993, are linked to outbreaks. This surge coincides with a notable decrease in vaccination coverage among US kindergarteners, which has fallen from 95.2 percent in the 2019-2020 school year to 92.4 percent in the 2025-2026 school year. The number of confirmed cases by November 2026 has more than doubled compared to the 2,289 cases reported in 2025.

A dispute has emerged regarding the official death toll. While the CDC data indicates four measles-related deaths in 2026, state officials, particularly in Pennsylvania, report a higher number. Pennsylvania's Department of Health has documented six deaths and 1,487 cases. The discrepancy stems from differing classification methods for measles-associated deaths, creating tension between Pennsylvania Governor Josh Shapiro and US Health Secretary Robert F Kennedy Jr.

Pennsylvania classifies a death as “measles-associated” if a person with confirmed measles dies within 30 days of symptom onset, unless an unrelated event caused the death. This contrasts with the CDC's initial inclusion and subsequent removal of two unvaccinated individuals' deaths from its national tally, a decision influenced by vaccine sceptic Robert F Kennedy Jr.'s questioning of measles' role in the fatalities. The CDC is collaborating with the US Council of State and Territorial Epidemiologists to standardize the definition of measles deaths.

Infectious disease experts express concern that this classification dispute deviates from established tracking methods used by the World Health Organization and the CDC for decades, potentially undermining efforts to monitor the disease's impact. The US declared measles eliminated over 20 years ago. Globally, measles cases are also on the rise, particularly in communities with vaccine hesitancy or limited healthcare access. Experts emphasize that declining vaccination rates in any region can create vulnerabilities far beyond immediate proximity, underscoring the global nature of measles prevention.