Measles cases in the US hit 35-year high, with more than 5,000 infections

A total of 5,182 confirmed measles cases have been reported in the United States so far in 2026, according to data released by the Centers for Disease Control and Prevention (CDC). It is the highest number reported by the agency since 1991, raising concern across the country over the highly contagious but vaccine-preventable disease.

Children and teenagers make up almost 60 percent of confirmed cases. Children below the age of five account for 18 percent of cases, while children between the ages of five and 19 account for 41 percent. Taken together, children and teenagers represent about 59 percent of all confirmed cases.

The majority of cases, a total of 4,993, were outbreak-associated, the CDC said. In other words, these were not isolated infections but part of clusters spreading in particular areas.

Experts point to falling vaccination coverage behind the resurgence. Vaccination coverage among US kindergarteners has decreased from 95.2 percent during the 2019-2020 school year to 92.4 percent in the 2025-2026 school year.

The number of confirmed cases by November 2026 is more than double the 2,289 confirmed measles cases reported in the whole of 2025. The sharp jump within a year has alarmed specialists.

According to CDC data, four people have died due to measles in 2026. But that national figure does not match the counts reported by state officials. Pennsylvania, the state hardest hit by the outbreak, reported six deaths and 1,487 cases this year.

The federal count has been at the centre of a dispute between Pennsylvania Governor Josh Shapiro and US Health Secretary Robert F Kennedy Jr over how measles deaths are classified.

Pennsylvania reports a death as measles-associated when a person with confirmed measles dies within 30 days of developing symptoms, unless the death resulted from an unrelated event.

In August, Pennsylvania reported that two unvaccinated people died of measles. The CDC initially included the deaths in its national tally but subsequently removed them after Kennedy, a vaccine sceptic, questioned whether measles had caused or contributed to the fatalities.

The CDC has said it is working with the US Council of State and Territorial Epidemiologists to establish a standardised definition for measles deaths.

Infectious disease experts warn that the dispute over how to classify the deaths puts the CDC at odds with a longstanding approach to tracking the consequences of measles. Epidemiologists have said that tracking measles-associated deaths has long been a standard used by the World Health Organization and the CDC.

The US declared the virus eliminated more than two decades ago. Measles cases have also increased globally, particularly in communities that are vaccine-sceptical or where there are gaps in healthcare access. Experts warn that declining vaccination rates in one geographic location can leave people thousands of miles away vulnerable, making measles prevention a shared global responsibility.