How holes in herd immunity led to a 25-year high in U.S. measles cases
Too many unvaccinated people are helping the virus spread
![Los Angeles County health officials](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2019/04/042919_AC_measles_feat.jpg?fit=860%2C460&ssl=1)
IT’S AN ORDER Public health officials in Los Angeles County on April 26 discuss the quarantine orders in place for hundreds of students at two Los Angeles universities after they potentially were exposed to measles.
Damian Dovarganes/ASSOCIATED PRESS