In a highly unusual move, the US Centers for Disease Control and Prevention is not counting two measles-associated deaths reported by the state of Pennsylvania in its measles death tally, saying it doesn’t have enough information to determine whether measles caused or contributed to the fatalities.

A coroner said one of the Pennsylvania deaths was not caused by measles. There is little data on the second measles-associated death.

Clash with Pennsylvania comes as US records highest number of measles cases in decades.