The numbers are preliminary. The 2019 tally is already the most since 2014, when 667 were reported. The most before that was 963 cases in 1994. Outbreaks have hit several states, including California, Michigan and New Jersey. New York City accounted for about two-thirds of the U.S. cases reported last week.
The Centers for Disease Control and Prevention updated the numbers Monday. Roughly 80% of the cases are age 19 or younger. The CDC recommends that all children get two doses of measles vaccine. It says the vaccine is 97% effective.