Government health officials have conceded that childhood vaccines worsened a rare, underlying disorder that ultimately led to autism-like symptoms in a Georgia girl, and that she should be paid from a federal vaccine-injury fund.

Medical and legal experts say the narrow wording and circumstances probably make the case an exception — not a precedent for thousands of other pending claims.

The government "has not conceded that vaccines cause autism," said Linda Renzi, the lawyer representing federal officials, who have consistently maintained that childhood shots are safe.

However, parents and advocates for autistic children see the case as a victory that may help certain others. Although the science on this is very limited, the girl's disorder may be more common in autistic children than in healthy ones.

"It's a beginning," said Kevin Conway, a Boston lawyer representing more than 1,200 families with vaccine injury claims. "Each case is going to have to be proved on its individual merits. But it shows to me that the government has conceded that it's biologically plausible for a vaccine to cause these injuries. They've never done it before."

A lawyer for the 9-year-old girl has scheduled a news conference in Atlanta on Thursday. Her parents have declined to comment in the meantime because the case is not final and the payment amount has not been set.

Nearly 5,000 families are seeking compensation for autism or other developmental disabilities they blame on vaccines and a mercury-based preservative, thimerosal. It once was commonly used to prevent bacterial contamination but since 2001 has been used only in certain flu shots. Some cases contend that the cumulative effect of many shots given at once may have caused injuries.

The cases are before a special "vaccine court" that doles out cash from a fund Congress set up to pay people injured by vaccines and to protect makers from damages as a way to help ensure an adequate vaccine supply. The burden of proof is lighter than in a traditional court, and is based on a preponderance of evidence. Since the fund started in 1988, it has paid roughly 950 claims — none for autism.

Studies repeatedly have discounted any link between thimerosal and autism, but legal challenges continue. The issue even cropped up in the presidential campaign, with Republican John McCain asserting on Friday that "there's strong evidence" autism is connected to the preservative.