Vaccine adverse events are rare and far outweighed by the benefits, but the unlucky few who experience them have no recourse for financial redress, Dr. Kumanan Wilson of the University of Ottawa told a major immunization conference.

A compensation system -- like one already in place in Quebec -- would also help counter a growing anti-vaccination movement that is exploiting the Internet to spread often ill-informed views, he said.

"It seems unjust that we don't have one," said Dr. Wilson after addressing the annual Canadian Immunization Conference. "As we're moving to more and more 'coercive-type policies' ... and with more and more vaccines, and HPV vaccine coming out, I think it's really a need."

But such systems also carry a downside for public-health professionals. A recent decision under the U. S. no-fault program awarded compensation to the parents of an autistic child who say their daughter's condition was caused by a vaccine ingredient, even though the majority of scientific studies have ruled out any link between autism and vaccine.

Any compensation plan here would have to avoid decisions that are based on faulty science and send out the wrong message, warned Dr. Monika Naus, associate director of the B. C. Centre for Disease Control.

"If it's a government compensation program, there is the opportunity for things to get derailed," Dr. Naus said. "I'm all for it; I just think it needs a lot of thought."

Regardless, the concept is far from taking off. The Public Health Agency of Canada, which organized the conference, has no plans to implement such a system, and there has been little discussion in the vaccine community of the idea, said Dr. Arlene King, a director-general with the agency.

Immunization is considered one of the great success stories of public health, wiping out or dramatically curbing such serious infectious diseases as smallpox, polio, tetanus, diphtheria, rubella and measles.

But some vaccines have been linked to a low incidence of side effects. Flu shots, for instance, may slightly increase the small chance of contracting Guillaine-Barre syndrome, which can cause temporary paralysis. Measles, mumps and rubella shots lead to low blood-platelet counts in one of every 30,000 infants who receive it.

The United States, U. K., Quebec and at least nine other jurisdictions have instituted no-fault compensation systems, meaning claimants can simply apply for redress -- backed up with medical evidence-- rather than launch an expensive and emotionally draining lawsuit.

The U.S. system was set up in response to a growing number of class-action and other lawsuits, which had forced many vaccine manufacturers to stop operating in America and led to a vaccine shortage.

The new system required people to seek compensation first in the no-fault system. If they accepted the award, they could not also file a lawsuit. The number of suits dropped precipitously as a result, although it has risen again in the past few years, Dr. Wilson said.

The recent surge in cases has revolved chiefly around the claim that thimerosal -- a preservative once widely used in vaccines -- causes autism, which most scientists reject.