Bradley Dyer and his colleagues at All Star Pediatrics in Exton refuse to care for refusers.

"If you should absolutely refuse to vaccinate your child despite all our efforts, we will ask you to find another health-care provider," reads the policy given to parents. "Please recognize that by not vaccinating, you are putting your child at unnecessary risk for life-threatening illness and disability, and even death."

Esther K. Chung's group, meanwhile, never gives up on refusers.

"I'm happy to say we don't turn families away if they don't want to vaccinate," said Chung, of Nemours duPont Pediatrics at Jefferson University Hospital. "But every single time they come in, we revisit the issue."

Childhood vaccination, one of the top public-health achievements of all time, has become an occupational headache and heartache for pediatricians. On a daily basis, they face balking that ranges from minor concerns about vaccine safety, to requests to alter the optimal timetable for immunizations, to intractable distrust and refusal.

Last week, pediatricians cheered as their professional organization boldly confronted the growing problem of vaccine "hesitancy." For the first time, the American Academy of Pediatrics called on states to get rid of nonmedical exemptions for vaccines, and said it is "acceptable" for physicians to show the door to families who reject this bedrock approach to disease prevention.

The academy's report in the journal Pediatrics also cited survey trends: In 2013, 87 percent of pediatricians dealt with parents who declined at least one mandated vaccine, up from 75 percent in 2006. Twelve percent of pediatricians resorted to dismissing vaccine refusers in 2013, up from 6 percent seven years earlier.

These figures likely understate the resistance, because the survey only covers vaccines that are mandated for school admission, said Jonathan Miller, director of pediatrics at Nemours duPont Hospital for Children in Wilmington. Half of parents decline the non-mandated flu and HPV vaccines, even though 20,000 preschoolers a year are hospitalized with the flu, and the HPV vaccine prevents cervical cancer and other malignancies.

To be sure, doctors realize that new parents may be taken aback by the recommended vaccine schedule, a complicated roster of 16 immunizations, most given by injection. Several ages - notably 2 months and 4 months - are loaded with wails, even though manufacturers have combined some vaccines to minimize shots.

"The maximum at one visit would be 4 or 5 shots," said pediatrician Bruce Lockman, whose Fort Washington practice serves 14,000 patients. "We're using needles, so there's going to be some discomfort. A small percentage of children will have soreness and a low-grade fever. Most can be managed with Tylenol."

While surveys show parents are concerned about pain, their hesitance is complex.

"Vaccine hesitation crosses socio-economic boundaries, but a large majority are well-resourced, well-educated families who don't have a medical background but have the confidence to question authority," Chung said. "They've searched the internet, and there's a lot of misinformation out there."

The academy's surveys suggest more parents are savvy about a particularly pernicious falsehood linking vaccines with autism. About 64 percent of doctors encountered autism fears in 2013, vs. 74 percent in 2006.

Other dangerous misconceptions flourish, such as the idea that getting a disease is a more "natural" way to develop immunity; that many vaccine-preventable diseases aren't serious; or that vaccines will "overwhelm" a healthy child's immune system.

That last myth was dispelled by a 2002 medical review led by pediatrician Paul Offit, a vaccine expert at Children's Hospital of Philadelphia. Research shows an infant has the capacity to respond to so many antigens - the foreign proteins that stimulate an immune response - that 10,000 vaccines theoretically could be given at once. Besides, the number of antigens in vaccines has been reduced from more than 3,000 in 1980 to about 126 now.

"For parents who want to split up vaccines, the concept of overwhelming the immune system plays to their common sense," said Dyer, in Exton. "But it's proven that that is not an issue."

Negative perceptions of drugmakers also color parents' attitudes.

"They think the vaccine manufacturers are in it for the money," said Miller, in Wilmington. "It's not like parents don't trust me, but they think maybe I'm being misled by the pharmaceutical marketing."

It doesn't help when influential public figures undermine vaccines. Last year, amid a multistate measles outbreak that began at Disneyland in California and was linked to falling vaccination rates, GOP presidential hopefuls, including New Jersey Gov. Christie, voiced doubts about vaccines.

Such complacency is an ironic side effect of conquering major causes of childhood suffering and disability, doctors say.

Lockman, who is 65, recalls learning sign language early in his career because rubella had left so many patients with congenital deafness. Bacterial meningitis, an infection of the membranes of the brain and spinal cord, was a constant worry.

"When I was in training, I did a spinal tap every day" to check for meningitis, he said. "There were 2-year-olds who were well at 4 p.m., and fighting for their lives at midnight."

The vast majority of hesitaters ultimately get their children fully vaccinated, doctors say. But the estimated 3 percent of parents who dig in their heels pose no-win dilemmas.

Lockman's Fort Washington practice, like Dyer's Exton group, asks refusers to go elsewhere.

While Chung's group at Jefferson accepts refusers, such parents must sign a waiver acknowledging they understand the risks. The form itself prompts some to relent.

"That's concerning," Chung said, "because it's not meant to be intimidating at all."

Miller's group - seven pediatricians and 17 doctors in training - also accepts refusers. The doctors flag patients' unvaccinated status in medical records, and have protocols to minimize the risk of spreading a vaccine-preventable infection.

"I've even been known to go out to the parking lot to make sure they don't bring chicken pox into the waiting room," Miller said.

But a waiver is not required because, he said, "it rubs parents the wrong way, and I don't think it provides legal protection."

Instead, the doctors doggedly keep trying to build trust and change minds.

"We find parents who are very rational are acting very irrationally," Miller said. "But the onus is on us. It is our job to educate them. We are required to spend the time it takes."