As a measles outbreak sweeps through Texas, officially sickening 124 people, mostly unvaccinated children, and hospitalizing 18, anti-vaccine groups are pushing a familiar and false theory: The highly contagious virus is being caused by the vaccine itself.

An unvaccinated school-aged child has died in the measles outbreak in Texas, which has seen 124 reported cases of the disease. It's the first measles death in the U.S. since 2015. Pediatrician and infectious disease specialist Dr.