Panel Urges Changes in Polio Vaccinations : Health: Federal advisers recommend greater use of injected Salk vaccine. Move is aimed at reducing number of cases of disease caused by oral vaccine.

WASHINGTON —  Spurred by growing concerns about cases of polio apparently caused by the widely used live-virus vaccine, a federal advisory panel on Wednesday recommended a major change in the way American children are immunized against the disease.

The proposal would revive the original vaccine created by Dr. Jonas Salk in 1954. That vaccine ended the polio scourge in the United States, but it has been little-used in this country in recent years. Since 1961, most children have received an orally administered live-but-weakened virus vaccine, which was invented by Dr. Albert Sabin.

But the Sabin vaccine is believed to be responsible for causing a small number of cases of the disease--about 8 to 10 annually--in the United States. Concern about the problem has been mounting.

One of benefits of the Sabin “live virus” is that it is also effective in provoking immunity in people who did not directly receive it but who have had contact with individuals who did--a phenomenon known as “herd” immunity.

The advisory committee to the Centers for Disease Control and Prevention recommended administering two doses of the injectable vaccine, followed by two doses of the oral vaccine. Currently, four doses of the oral vaccine--which is easier to administer to small children--are recommended during the first two years of life. The new regimen, which is expected to be adopted by the CDC, is aimed at reducing or eliminating the vaccine-associated cases.

“Our long-range goal will remain the [global] eradication of polio altogether, so no vaccine would be necessary at all,” said Dr. Steven Hadler, chief of the agency’s epidemiology and surveillance unit. “In the meantime, the sequential schedule will prevent most of the cases of vaccine-associated polio in the United States.”

Experts do not understand why three or four of the children who receive the vaccine every year develop polio. Under the recommended new policy, the Salk vaccine--which poses no danger of disease--will be given first and is expected to provide enough immunity to prevent the disease when the oral doses are administered later, experts said.

An additional three or four cases occur in individuals who have contact with vaccine recipients and the remainder develop in people with compromised immune systems. The new schedule likely will be less effective in preventing disease among them, experts said.

Opponents of changing the schedule have argued that it will mean more shots in an already crowded schedule that youngsters must endure, and that will require additional visits to the doctor because many pediatricians will not give multiple injections on the same day.

Ultimately, this could result in fewer immunizations and more cases of polio, they said.

“The decision is a serious mistake, and we are very concerned about the impact it could have on public health in the United States and globally,” said Peter Paradiso, senior director for scientific affairs at Wyeth-Ayerst Laboratories of St. Davids, Pa., a manufacturer of the oral vaccine.

“The immunization schedule will be more complicated and therefore fewer children will be immunized,” he added.

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The injectable product is made by Connaught Laboratories Inc., of Swiftwater, Pa., a unit of the French drug-maker Pasteur Merieux. Connaught also makes a version of the oral vaccine.

Connaught’s president, David J. Williams, said the federal panel’s decision “marks the beginning of the last chapter in eradicating polio from the United States.”

The new program follows similar schedules that have been adopted by 11 other countries, including France, Denmark, Norway and most of Canada.

About 20 million doses of polio vaccine are administered each year in the United States, of which only 400,000 are the injectable version. The latter is most frequently given to those with damaged immune systems who could be harmed by taking the live product.

The virus that causes poliomyelitis, or infantile paralysis, attacks the central nervous system and can produce paralysis and death by asphyxiation. There are no effective drugs to treat it.

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Patients whose respiratory cells have been destroyed usually require a respirator to control breathing and keep them alive. The image of a child in a so-called iron lung became a terrifying specter in this country during the 1950s.

The epidemic, which reached a peak of 20,000 cases in the United States in 1952--most of them children--inspired near-hysteria nationwide among parents who kept their children home--and away from public swimming pools--during the summer months, when cases appeared to spread more rapidly.

While the disease afflicts mostly children, adults also are susceptible. The most famous American stricken was President Franklin D. Roosevelt, who fell ill when he was 39.

In 1994, the World Health Organization declared that naturally occurring “wild” polio had been eradicated from the Western Hemisphere. The last documented case occurred in Peru in 1991.

In the United States, the last case of “wild” polio occurred in 1979. Nevertheless, about 120,000 cases still occur annually in other parts of the world.