U.S. facing obstacles from declining vaccination rates

The United States is currently seeing twice the number of measles cases that occur in a typical year, marking the largest outbreak of the disease in 15 years.

The U.S. Centers for Disease Control has reported 152 confirmed measles cases so far this year. Half of the patients have been hospitalized, according to USA Today.

The return of vaccine-preventable diseases is a concern for doctors and public health officials, but one that is considered predictable.

"Measles can be like a canary in a coal mine," Gregory Wallace of the CDC said, USA Today reports. "If there are any issues with vaccine coverage, it can first be apparent with measles."

Recent years have also seen the resurgence of other vaccine-preventable diseases, such as mumps, whooping cough and Hib. Although vaccine coverage remains high among Americans, about 40 percent of parents admit to deliberately delaying or skipping vaccines for their children.

To Paul Offit, an infectious disease specialist at the Children’s Hospital of Philadelphia, vaccines are a victim of their own success. Today’s parents have little experience with diseases like the measles, that once killed 3,000 to 5,000 Americans every year.

"We've not only eliminated these diseases; we've eliminated the memory of these diseases," Offit said, according to USA Today.

Fear of the vaccinations themselves has also become a major reason that parents have avoided immunizing their children. Around the world, millions of parents stopped vaccinating because of an infamous, and now retracted, article in the British medical journal The Lancet that linked autism to the MMR vaccine.

Offit told USA Today that it has become one of the greatest myths in modern medicine. Despite the retraction and nearly two dozen studies showing no link between vaccines and autism, the belief persists.

"It's very easy in our media-driven, easy-access-to-information society to scare people," Dr. Tanya Remer Altmann, a spokeswoman for the American Academy of Pediatrics, said, according to USA Today. "It's much more difficult to unscare them."

Research has shown that more parents are exercising their rights to refuse vaccines. Forty-nine states allow children to be exempt from vaccinations for religious reasons, and 21 allow for philosophical exemptions. The number of philosophical objections doubled from 1991 to 2004, according to the Journal of the American Medical Association.

Granting exceptions to vaccinations has supported outbreaks, partly because like-minded parents cluster together, creating enclaves where very few children have up-to-date inoculations.