Likewise, a similar study found that pediatricians could convince almost 50 percent of parents who initially refused vaccinations after engaging with the parents in discussion.

More and more parents think vaccines are unnecessary.

Although all 50 states and the District of Columbia require that schoolchildren be immunized against a broad range of diseases, most states allow parents to opt out if they have a religious objection to vaccines and 18 allow for "philosophical exemptions" for those who object based on personal, moral or other grounds, according to the National Conference of State Legislatures.

According to the Academy, more pediatricians are seeing patients refuse vaccines.

Doctors who choose not to treat families that don't vaccinate their children are now getting support from the American Academy of Pediatrics. This is a significant increase from 2006, when 75 percent of doctors reported refusals. The category of parents who refused vaccination because they don't see the need rose by 10 per cent during that time frame.

In 2013, 9.2 percent of pediatricians couldn't convince any anti-vax parents with additional education.

The contrast between parents' attitudes about vaccines today and a decade ago is striking.

Dr. Catherine Hough-Telford, 32, from the University of Alabama at Birmingham, and who has a private practice in Florida has also claimed that pediatricians face vaccine delays and refusal "every day".

For example, in the new survey, parents seemed to most commonly delay vaccination because they were concerned about their children's discomfort, and out of the mistaken belief that vaccines may burden children's immune systems. The AAP is the largest organization of pediatricians in the United States. To get a better sense of what is happening in regard to parental vaccine hesitancy and refusal over time, Hough-Telford et al.

"Talking with parents, explaining about vaccines, answering their questions, and providing ways that we can address their concerns", Edwards told KCBS.

Nonetheless, this is against the AAP guidelines, which ask for patience from doctors to patients, advising them to "continued to engage" with this parents with the aim of changing their decision.

"It was gut-wrenching", said Dr. Alison Ziari, chief of pediatrics at the Austin Regional Clinic, a multi-specialty practice with 70 pediatricians in Texas that adopted a vaccinate-or-leave policy in July 2015. The average number of parents that refused all vaccines went from 2.1 to 3.3 percent. "Parents can and do fire doctors who don't admit the medical facts about vaccine reactions".

"It's clear that states with more lenient exemptions policies have lower immunization rates, and it's these states where we have seen disease outbreaks occur as the rates slip below the threshold needed to maintain community immunity", said Geoffrey R. Simon, lead author of the medical exemptions policy statement and immediate past chair of the AAP Committee on Practice and Ambulatory Medicine.

"We need to make it harder for parents not to vaccinate".