New York has just declared a state of emergency as measles cases continue to rise. So far this year, the US has recorded 3,887 cases of measles, the highest annual total since 1991. That is about 70% more cases than were recorded during the whole of 2025.

In November, the Pan American Health Organization will review whether the US has lost the measles elimination status it has held since 2000.

Cases are one thing, but the number of deaths is more complicated. A dispute has developed between the state of Pennsylvania and federal health officials over how many people have died. Pennsylvania, where the outbreak has reached 1,004 cases, has reported five measles-related deaths since late August. But the Centers for Disease Control and Prevention (CDC) has counted two measles deaths nationally in 2026.

The CDC has not said where those two deaths occurred, so it is unclear whether either is among the five reported in Pennsylvania. No other state has reported measles deaths this year.

What the argument is about

Part of the disagreement comes down to how a measles-related death is defined. Pennsylvania counts a death as measles-associated if the person had a laboratory-confirmed measles infection and died within 30 days of developing symptoms, unless there is another clear cause of death, such as a car crash.

The state says it based its definition on national definitions used for deaths from flu and RSV (a common respiratory infection). The CDC adds a death only once its National Center for Health Statistics has verified that measles was listed as the........

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