But Hannah Poling’s case is not typical. She has an underlying genetic condition known as a mitochondrial disorder, and investigators thought the vaccine might have aggravated that condition, leading her to develop autistic symptoms.

"We don’t know what the deliberations of the panel were," Westfall said. "Under this fund, there’s much less need for proof than there is in a court of law."

Documents related to the case have not been made public.

Hannah’s parents, Jon and Terry Poling of Athens, said that their daughter was developing normally until she received a series of immunizations when she was about 19 months old. They believe Hannah’s behavioral regression was caused by thimerosal.

Most vaccine manufacturers stopped using thimerosal about seven years ago, yet the number of diagnosed autism cases has skyrocketed.

"We continue to see a rise in autism even though the preservative that some people thought was linked to autism has been taken out of vaccines," Westfall said.

But to many parents, Hannah’s story sounds all too familiar. North Hall resident Kelly Barrett said her son Will seemed fine until he was 3, when he suddenly developed a speech impediment and behavior problems.

After several misdiagnoses, Barrett took him to an autism specialist in Virginia, who diagnosed Will with Asperger’s syndrome, a high-functioning form of autism.

Barrett said her son, now 10, is doing well and is able to attend mainstream classes at Mount Vernon Elementary.

"But there’s been a lot of hard work involved with teachers and therapists," she said. "And because autism is not considered a medical disease, it’s not covered by insurance. I’ve had to pay out of pocket for everything."

Barrett said she has mixed feelings about the federal settlement.

"My reaction is that nobody really knows (what causes autism)," she said. "The specialist and I both believe that autism is a predetermined problem that has an environmental trigger. I think it could be a combination of things, but I do think immunizations are a huge contributing factor."

Students are supposed to get boosters of certain vaccines once they get to middle school, and Barrett hasn’t decided what she’s going to do at that point.

"It’s a Catch-22," she said. "Of course you don’t want your kids to get mumps or polio. Yet I worry that I might make the autism worse."

Watson has decided not to let her children have any more vaccines, even though she works as a nurse and understands the reasons for immunization.

Her oldest daughter, now 13, developed autism at 18 months.

"Five years later, with my second daughter, I was hesitant about vaccines but decided to go ahead," she said. "After her second DPT (diphtheria-pertussis-tetanus) shot, she began having seizures and had to be hospitalized."

Since then, Watson has taken the religious exemption that allows families to opt out of vaccinations but still have their children attend school. To keep her daughters healthy, she said, "We take a holistic approach: chiropractic, acupuncture, homeopathy."

Even some Hall County families that have not been touched by autism are saying no to vaccines. Lydia White believes that when her daughter was 15 months old, she was given a "live" instead of a "killed" version of the whooping cough vaccine, and three members of the family ended up getting the illness.

White recently gave birth and has chosen not to vaccinate the new baby.

"If your child is the one out of 1,000 that has a reaction (to a vaccine), it matters to you," she said. "Every human body is genetically different. How do you know how each individual will respond to immunization?"

Brandy Oliver has made a similar decision about her two children, who are now 4 and 6.

"We did a lot of research and felt the health risks of vaccination far outweighed the benefits," she said. "These diseases the vaccines immunize against, most of them are not life-threatening. But the side effects are. To me, the possibility of my child getting autism was much more serious."

Autism is not fatal. But it is considered incurable, and the person may need lifelong care, unable to hold a job or to live independently.

Westfall said it would be tragic if fear of autism kept parents from immunizing their children.

"The potential consequences of not vaccinating are far worse," he said, noting that if the majority of people opted out of vaccinations, "We would see the return of a lot of infectious diseases that used to be a very significant cause of morbidity and mortality."

Westfall said District 2 Public Health will continue to convey the same message as the CDC, that there is still no scientific link between vaccines and autism.

White said she’s not buying it, and points out that many clinical trials are funded by drug companies.

"You have to be really careful about the studies and who did them," she said.

Westfall said the evidence against an autism link is overwhelming.

"Multiple studies have been done by multiple different investigators, including independent researchers," he said.

Dr. James Bell, a Gainesville pediatrician, said he will continue to advise parents that vaccination is in the best interest of the child.

"The vaccines definitely have a benefit," he said. "Some of the diseases we immunize against can be very serious. We don’t give shots because we enjoy sticking needles in people."

But health professionals and parents can agree that publicity surrounding the Hannah Poling case could help.

"This may refocus attention on the need for more research," Westfall said.

Barrett, too, is happy to see autism making headlines.

"My hope is that more awareness will bring more information," she said.