Measles is one of the most contagious of vaccine-preventable diseases, with the average person with measles capable of infecting 12-18 people if susceptible, and the contagiousness of measles infection highlights gaps in vaccination in the United States that have appeared over the last decade, because of skepticism about childhood vaccination in coastal states like California and Oregon and Washington. In those states, otherwise educated people worry that vaccines may cause autism and would prefer that other children provide herd immunity for theirs.

Although indigenous circulation of measles virus was declared eliminated from the country in 2000, the United States has seen more measles cases this year than in the last two decades, write a team in the New England Journal of Medicine.

Measles outbreaks can be costly and can harm not only children whose parents have declined vaccination but other children who are too young or unable to be vaccinated. Doctors and public health authorities should ensure that the measles vaccine, known to be effective, is accessible to all who need it, write Walter Orenstein, MD, and Katherine Seib, MSPH of Emory Vaccine Center.

"Despite the overwhelming evidence that vaccines – including the measles. Mumps and rubella vaccine – are safe, too many people still believe that greater risk is posed by vaccinating than by not vaccinating," the authors write.