New York City Mayor Bill de Blasio on Tuesday declared a public health emergency following a measles outbreak in several parts of Brooklyn.

The declaration requires residents living in the identified zip codes to receive the measles-mumps-rubella (MMR) vaccine. According to a press release issued by the Mayor’s Office, the mandatory vaccination will be issued to protect those currently unaffected and limit the scope of the outbreak.

Only a few exceptions will be given to the vaccination requirement—those who have demonstrated immunity against the virus and when the vaccine is medically contra-indicated. When issuing the vaccinations, New York’s Department of Health and Mental Hygiene will review records for anyone potentially in contact with an infected individual. Foregoing the mandatory vaccination may result in a violation and fine up to $1,000.

Currently, the outbreak been confined to the Orthodox Jewish Community, with 285 cases confirmed since October. In comparison, there were only two reported cases in 2017. The disease has caused multiple hospitalizations and the outbreak continues to re-surge with anti-vaxxer movement.

“There’s no question that vaccines are safe, effective and life-saving,” said Mayor de Blasio. “I urge everyone, especially those in affected areas, to get their MMR vaccines to protect their children, families and communities.”