Vaccine critics have downplayed the role of measles in two Texas girls’ deaths, peddled unproven measles treatments and exaggerated the dangers of the vaccine.

Measles cases are likely being underreported in the U.S. as public health officials scramble to find resources to manage a ballooning outbreak in Texas according to a CDC scientist.

With two measles deaths - both children - in the state, officials struggle to convince communities to vaccinate.