A preliminary analysis suggests that substandard vaccination compliance contributed to the 2015 measles outbreak that began in Disneyland in December 2014.

MIT researchers presented their analysis of outbreak data in a research letter published online March 16 in JAMA Pediatrics. They report that the rapid increase in cases suggests that a substantial percentage of the exposed population was susceptible to measles infection. The team also evaluated whether suboptimal vaccine coverage may have contributed to the outbreak.