Sarah Behie's symptoms started nearly three weeks after she got a flu shot.

The nurse's aide at Lehigh Valley Hospital noticed that her knees and arms hurt and that her limbs felt weak.

As the pain and weakness grew worse, the 20-year-old was admitted to the hospital and later diagnosed with Guillain-Barre syndrome, a rare neurological condition that would leave her partially paralyzed and living in hospitals and nursing homes for nearly four years.

The cause of Behie's illness, her lawyers alleged, was the flu vaccine that she received at work in October 2010.

On Tuesday, attorneys Lawrence Cohan and David Carney of Philadelphia announced they had negotiated a settlement that will provide up to $11.6 million over Behie's lifetime to pay for her ongoing medical care.

The settlement, to be paid by the tax-funded National Vaccine Injury Compensation Program, will also provide Behie more than $1 million for her lost wages, pain and suffering and other medical expenses.

Carney said the money will allow Behie to continue her treatment at Good Shepherd Rehabilitation. Behie, who lived in Lower Macungie Township before her illness, has no use of her legs and lacks the strength in her upper body to feed or clothe herself. She's 24.

"It's hopeful that she will be able to return home at some point, but it's not in the plan for the immediate future," Carney said.

Behie's case — though rare — is an example of the risks associated with vaccines. Studies in the United States and Canada show a small but significant risk of contracting Guillain-Barre syndrome after receiving a flu vaccine.

The benefits of immunization, however, likely outweigh the risks, says a study published in the Journal of the American Medical Association. Another study put the rate of Guillain-Barre syndrome cases at one or two per million doses of flu vaccine.

"Vaccines are not bad," said Carney, who specializes in representing people who suffer vaccine injuries. "I would recommend listening to your doctor's advice."

Although Lehigh Valley Hospital now requires each of its employees to be vaccinated for influenza, it was not a requirement in 2010 when Behie became ill. The hospital was not named as a defendant in her suit.

Behie's settlement is the result of a safety net created by Congress a quarter century ago to spread the cost of those risks and ensure that vaccine manufacturers can keep doing business.

"This is exactly what the compensation program was designed to do," said John G. Culhane, an expert in health policy law at Widener University Law School.

Vaccine safety has improved greatly since Louis Pasteur developed the principles of immunization in the late 1800s, but there remain recognized risks to vaccination, Culhane said. In the 1980s, both plaintiffs' lawyers and pharmaceutical companies were concerned about litigation over vaccine injuries.

Lawyers worried that the burden of proof that a vaccine caused a person's illness would become impossible to meet, and that courts, recognizing the value of immunization, would be reluctant to issue rulings that could reduce the availability of vaccines.

Vaccine manufacturers were concerned that the cost of verdicts and settlements in favor of people hurt or sickened by their products would force them out of the business, Culhane said.

"The vaccine compensation program was established with support from both sides," he said.

Legislation authorizing the U.S. Department of Health and Human Services to begin the program in 1988 set a 75-cent tax on each dose of immunization to go into a compensation fund.

"The idea was that because the entire population benefits through herd immunity … we all should pay," Culhane said.

In exchange for their support, vaccine manufacturers received limited protection from lawsuits in state and federal courts.

All suits over illness or injury caused by vaccines must be filed in the U.S. Court of Federal Claims in Washington, D.C. About 27 percent of cases result in compensation, according to HHS.

The court's decisions can be appealed in civil court, but the claimants can pursue damages only for manufacturing defects or a failure to warn users about potential risks.

Since 1989, the compensation fund has paid out nearly $2.9 billion in awards and attorney fees. The average award last year was $679,110, HHS reported.

Carney estimated Behie's settlement is in the top 20 percent of all awards from the vaccine compensation program. In her case, the government chose not to defend the case, but instead devote its resources to negotiating an appropriate settlement, he said.

The facts in her case were clear, Carney said. Behie had been a healthy, working woman; the onset of her symptoms closely matched the time frame described in medical literature for cases of Guillain-Barre syndrome caused by flu vaccine; and there was no other explanation for her illness.

"The government bitterly contests these cases. They don't often concede them," Carney said.

peter.hall@mcall.com

610-820-6581