LOS ANGELES, CA-FEBRUARY 6, 2015: A vial containing the MMR vaccine, right, and another vial containing the diluent used to mix the vaccine, sit on a tray before being loaded into a syringe at the Medical Arts Pediatric Med Group on Wilshire Blvd. in Los Angeles on February 6, 2015. (Photo by Mel Melcon/Los Angeles Times via Getty Images)