Measles, a disease once thought to be eliminated in the U-S, is making a comeback. Last year, the Centers for Disease Control reported 644 cases. Measles is a highly contagious respiratory illness. It’s caused by a virus and spreads through the air through sneezing and coughing, and can lead to serious complications, even death. All 50 states require that students get vaccinated. But there are exceptions, according to the National Conference of State Legislatures. All but 2 states grant exemptions for people with religious beliefs against immunizations. And a growing number of states — now 20 of them — let people with philosophical objections to vaccines to opt their kids out. Anti-vaccines movements aren’t just an American phenomenon. Laurie Garrett, a senior fellow for global health at the Council on Foreign Relations, joins us to talk about why so many preventable diseases are still a risk in developed countries. PHOTO: Pediatrician Charles Goodman, talks with patient Carmen Lopez, 37, holding her 18-month-old son, Daniel after being vaccinated with the measles-mumps-rubella vaccine, or MMR at his practice in Northridge, Calif., Thursday, Jan. 29, 2015.(AP Photo/Damian Dovarganes)