US changes measles death-count methodology as Pennsylvania outbreak grows

The US Centers for Disease Control and Prevention has changed how it tracks measles-related deaths, switching data sources in early September just as an outbreak in Pennsylvania produced a third suspected fatality. Since 4 September, the agency has relied on figures from the National Center for Health Statistics (NCHS), a system historically used for long-term mortality trend analysis rather than confirming individual cases.

Debra Houry, a former CDC chief medical officer, called the shift "puzzling," saying the NCHS system was never designed to verify specific deaths. Previously, the CDC relied on the National Notifiable Diseases Surveillance System, which channels case data from local and state health authorities to federal officials.

The CDC's website now carries a note stating that NCHS has no 2026 death records listing measles as the underlying cause. Yet Pennsylvania health officials have already confirmed two measles-associated infant deaths this year, and on Saturday a 40-year-old unvaccinated woman with chronic obstructive pulmonary disease died in Jefferson County. Coroner Greg Furlong said the woman had not sought medical treatment before her condition worsened, and that despite her underlying health issues, he believed she would still be alive had she not contracted measles. The death is being classified as probable measles-related pending swab test results, based on her known contact with a confirmed case.

Pennsylvania had recorded 676 confirmed measles cases as of Friday, though Furlong said he believes the real number is higher due to underreporting. An HHS spokesperson said the CDC would only report measles deaths once NCHS officially attributes them to the disease.

HHS Secretary Robert F Kennedy Jr has not publicly addressed the latest death. He had previously questioned, without evidence, whether the two earlier deaths were actually caused by measles and reportedly asked the CDC director to exclude them from official counts — a request made shortly before the agency's data source change. Kennedy, who spent nearly two decades leading an anti-vaccine organization, has repeatedly spread vaccine misinformation, though HHS maintains that its recommendation for the MMR vaccine remains unchanged.