The city's health department is investigating an outbreak of chicken pox in the Orthodox Jewish community of Williamsburg.

Seventy-five children have been stricken since March. Nearly three-quarters of them did not receive a vaccination against the virus, and an additional 14 percent did not receive the recommended number of doses, according to the health department, which says two doses of the vaccine are 98 percent effective. 

The city sent out an alert to physicians reminding them to make sure children are up to date with their vaccinations.

The city in September urged Orthodox schools and parents to vaccinate their children after a whooping cough outbreak.

Some yeshivas have the lowest reported vaccination rates among schools in the city, according to state data.

In 2013, the city health department reported 48 cases of measles in the Orthodox Jewish community residing in Borough Park and Williamsburg.