Pennsylvania reports fourth measles death as U.S. sees rise in cases

Pennsylvania health officials announced Tuesday that a fourth person has died from measles, the first time the United States has recorded four measles deaths in a single year since 1992. The state has documented at least 693 cases, 133 hospitalizations and four deaths, though officials acknowledge the true numbers may be higher because milder cases often go unreported.

Measles deaths have been rare in the United States since the introduction of a highly effective vaccine in 1963. The last year with four or more measles deaths before this was 1992, and the country went several years without any measles fatalities until three deaths occurred last year, the most recent prior to this being in 2015.

Johns Hopkins epidemiologist Dr. William Moss said Pennsylvania’s death toll is “on the high side” and reflects that the fatalities involved individuals with underlying health conditions, including two infants with serious genetic or medical issues, a 40-year-old woman with chronic obstructive pulmonary disease, and an 18-year-old who died from acute disseminated encephalomyelitis, a known but rare complication of measles.

Both Dr. Moss and Dr. David Margolius, director of the Cleveland Department of Health, said there is no evidence the virus has mutated to become more lethal; the increase in deaths is likely linked to higher case numbers and declining vaccination rates. The measles vaccine provides about 97% protection after two doses, and the risk of death among vaccinated individuals is very low unless they are immunocompromised.

Globally, the World Health Organization estimates 95,000 measles deaths in 2024, with 95% occurring in low-income countries. Before widespread vaccination, measles caused an estimated 2.6 million deaths worldwide each year. The United States declared measles eliminated in 2000, but recent outbreaks may prompt a reassessment of that status later this year.