Amid one of the largest measles outbreaks in the United States in nearly a decade, anti-vaccine activists are promoting false claims that shots are ineffective in stemming the spread of the virus or that they could cause the disease.

Measles has sickened nearly 150 mostly unvaccinated people in rural West Texas, and a school-age child has died.

Infectious disease doctors said the measles virus can cause serious complications, and they say now is the time to make sure your children are vaccinated.