President Barack Obama's press secretary says the science on vaccinations "is really clear." Josh Earnest tells journalists that Obama believes vaccination decisions should be made by parents, with a bias toward good science.
About 100 cases of the measles have been reported in the U.S. since last month in the second-biggest outbreak in at least 15 years. Most have been traced directly or indirectly to Disneyland in Southern California.
Earnest says federal officials are closely monitoring the outbreak.
The Centers for Disease Control and Prevention says measles-mumps-rubella vaccine is 97 per cent effective at preventing measles.