The ban went into effect at midnight, Wednesday, barring anyone younger than 18 who is unvaccinated against the measles from public places until they receive the measles, mumps and rubella vaccine. The ban expires in 30 days.

Those unable to be vaccinated for documented and confirmed medical reasons are exempt from the declaration.

“We believe this to be the first such effort of this kind nationally and the circumstances we face here clearly call for that,” said Rockland County Executive Ed Day at a Tuesday press conference. “Rockland will lead the way in service and safety to the people here.”