New York City Mayor Bill de Blasio issued a public health emergency on Tuesday in response to a measles outbreak in parts of Williamsburg, Brooklyn. De Blasio is requiring unvaccinated people living in the largely Orthodox Jewish area to get vaccinated or face a fine of up to $1,000. Nearly 300 people, most of them children, in the neighborhood have so far been infected with the sometimes fatal disease, compared to only two reported cases in 2017. On Monday, New York City health officials announced a crackdown on yeshivas that are letting unvaccinated students attend school in the midst of the major measles crisis.

—Audrey McNamara