(CNN) — Officials say it’s the worst measles outbreak they’ve seen in years.
The Centers for Disease Control and Prevention reports 159 measles cases since Jan. 1 in the United States.
Those cases are in California, Colorado, Connecticut, Georgia, Illinois, Kentucky, New York, Oregon, Texas and Washington.
The CDC says measles is highly contagious but a two-dose vaccine is 97 percent effective against the virus.
The disease was eliminated in the U.S. in 2000, but is local in many other countries, which is how officials believe the current outbreaks started.