Sept. 3 (UPI) -- New York City health officials and Mayor Bill de Blasio declared the city's largest measles outbreak in 30 years over Tuesday, after hundreds of diagnoses.

The New York City Department of Health and Mental Hygiene said a measles outbreak is declared over when 42 days has passed since the last infectious day of the last persons with measles in an affected area. That's the equivalent of two incubation periods.


"Ending the measles outbreak required extensive collaboration with community organizations and Jewish leaders. They helped encourage vaccinations and achieve record immunization levels in parts of Brooklyn," de Blasio said. "As we head back to school this week, we just remain vigilant. To keep our children and communities safe, I urge all New Yorkers to get vaccinated. It's the best defense we have."

During the outbreak, which began October 2018, doctors diagnosed 654 people with measles, 52 of whom were hospitalized and 16 placed in intensive care. Most of those diagnosed were children (80 percent).

Seventy-three percent of those infected were unvaccinated, seven percent were incompletely vaccinated and 15 percent didn't know their vaccination status. A majority of the cases, 72 percent, were in the Brooklyn neighborhood of Williamsburg.

The outbreak prompted New York Gov. Andrew Cuomo to sign a law ending non-medical exemptions from mandatory vaccinations for school children. Health officials administered more than 15,000 doses of the vaccine in the Williamsburg and Borough Park neighborhoods.

"Measles is one of the most contagious diseases on the face of the earth," Health Commissioner Dr. Oxiris Barbot said. "There may no longer be local transmission of measles in New York City, but the threat remains given other outbreaks in the U.S. and around the world. Our best defense against renewed transmission is having a well immunized city."

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As of Thursday, the U.S. Centers for Disease Control and Prevention said there have been 1,234 reported cases of measles in the United States this year. Only one of the cases, it said, was "recently ill."