A county in New York state has declared a state of emergency following a severe outbreak of measles.
Rockland County, on the Hudson river north of New York City, has barred unvaccinated children from public spaces after 153 cases were confirmed.
Violating the order will be punishable by a fine of $500 (£378) and up to six months in prison.
The announcement follows other outbreaks of the disease in Washington, California, Texas and Illinois.
Vaccination rates have dropped steadily in the US with many parents objecting for philosophical or religious reasons, or because they believe misleading information that vaccines cause autism in children.