Growing disease rates will also encourage more parents to get their children immunized. Paul Offit, chief of the division of infectious diseases at the Children’s Hospital of Philadelphia in Pennsylvania, says that people are "far more compelled by fear than reason".
Disease outbreaks are now hitting the headlines more frequently than vaccine safety concerns. This year, the number of pertussis cases in the United States looks set to be the highest since 1959, and in 2011 the country saw 222 cases of measles — the most since 1996.
Yet not everyone is in favor of vaccination. In the past two years, legislators in Kansas, Mississippi, West Virginia, Massachusetts and South Dakota have introduced bills to add philosophical exemptions — but without success.
In Washington, where the law to strengthen exemption requirements came into force in July 2011, the change is already bringing results: kindergarten exemption rates dropped to 4.5% this year. Time will tell whether the numbers in other states will follow suit.