The nation’s worst measles epidemic in 27 years could be in its final stages as a week went by with no new reported cases.

“To get to zero is tremendously encouraging,” said Jason Schwartz, a Yale University expert on vaccination policy.

The current epidemic emerged about a year ago and took off earlier this year, with most of the cases reported in Orthodox Jewish communities in and around New York City. It started with travelers who had become infected overseas but spread quickly among unvaccinated people.

In the spring, 70 or more new cases were being reported every week. Not long ago, the nation that saw that many measles cases in a whole year.