The state of emergency, which will be announced by the county’s executive, Ed Day, will take effect at midnight on Tuesday.
Day is expected to discuss the details of the state of emergency at 2 p.m. in a news conference.
Rockland County, which has a population of more than 300,000, has had 153 confirmed cases of measles since last October, a county spokesman, John G. Lyon, said. Of those, 48 have come in 2019.
As part of the county’s efforts to fight the outbreak, officials issued so-called exclusion orders in December that banned unvaccinated children from schools with low vaccination rates.
This article originally appeared in The New York Times.