Texas health officials reported 17 new measles cases on Tuesday, bringing the total confirmed cases since late January to 663. The state’s public health department estimates that fewer than 10 of the confirmed cases — about 1% — are “actively infectious.

The Centers for Disease Control and Prevention confirmed nearly 900 measles cases in the U.S. on Friday, though much of the measles cases in the country remain centered in Texas, which confirmed earlier this week there have been 624 cases of the highly contagious illness in the state this year.

Nearly all measles infections seen during the Texas outbreak are among individuals who have not been vaccinated, or whose vaccination status is unknown.