A fourth death confirmed

Pennsylvania's health department confirmed Tuesday that an unvaccinated 18-year-old from Mifflin County died of measles, the state's fourth death this year.

Who else has died

The same announcement confirmed an unvaccinated 40-year-old woman in Jefferson County. The first two were infants in Lancaster County, a newborn boy and a 6-week-old girl, both too young to be vaccinated.

The brain complication that killed him

The coroner ruled the cause was acute disseminated encephalomyelitis, a rare measles complication where runaway inflammation strips the protective coating off nerve cells in the brain and spinal cord.

The outbreak is still growing

693 cases across 38 counties so far this year, with 99 in the last seven days alone. 133 people have been hospitalized.

“Pennsylvania faces the worst measles outbreak in more than three decades”

The federal response

Health Secretary Robert F. Kennedy Jr. has disputed deaths, spread misinformation about the MMR vaccine, and reportedly ordered the CDC director to leave the two babies' deaths out of reports.

Changing how deaths are counted

The CDC used to rely on state and local health officials. Now it will only count records from a vital statistics system built to track long-term trends, not live outbreaks.

Elimination status is slipping

Nearly 3,300 US cases this year beats last year's record and is the most since 1991. With vaccination below the 95 percent target, the country is on track to lose the elimination status it earned in 2000.