A federal advisory panel recommended Thursday that the United States abandon the oral polio vaccine that has been the world's medicine of choice in battling the disease for nearly four decades and return to the injectable vaccine that ended the scourge of polio in this country and made Dr. Jonas Salk a national hero.
Salk developed his vaccine in 1954, but, despite his pioneering work, his product was largely supplanted within a decade by a vaccine developed by Dr. Albert Sabin that was less expensive, more effective and could be taken orally.
The subsequent global dominance by the oral vaccine provoked an extremely bitter and often nasty public feud between the two scientists that lasted for years until Sabin's death in 1993.
The panel's decision Thursday effectively makes Salk the posthumous winner in the longtime rivalry, although only in the United States, where polio epidemics are no longer regarded as a probability.
The move to return to the Salk vaccine was prompted by growing concerns in recent years over a small number of polio cases apparently caused by the oral vaccine.
CDC Expected to Follow Panel's Advice
The panel's recommendation is not binding but is expected to be accepted by the Centers for Disease Control and Prevention, which drafts immunization policy guidelines for the public health community.
The Department of Health and Human Services will make the final decision but typically follows the CDC's advice.
Most of today's young adults received the oral version of the vaccine--often on a cube of sugar--while their parents got the shots, from the mid-1950s to the early '60s, after Salk's discovery.
There are numerous advantages to the Sabin vaccine, particularly overseas, but its use in the United States has resulted in eight to 10 cases annually of children who contract the disease.
The risk is extremely rare, about one case for every 2.4 million doses, according to the CDC.
The World Health Organization declared in 1994 that naturally occurring "wild" polio had been eradicated from the Western Hemisphere. The last documented case was in 1991 in Peru.
"The oral polio vaccine was vital to the elimination of the wild polio virus in the United States and other parts of the world and continues to be important. . . . However, oral polio vaccine, in rare instances, does cause paralytic polio. We couldn't ignore that," said CDC spokeswoman Barbara Reynolds.
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. Patients whose respiratory cells have been destroyed usually require a respirator to control breathing and keep them alive.
To become immune to polio, children must have four doses of the vaccine before the age of 6.
Most parents have little choice over the issue of whether to vaccinate their children against polio, since all 50 states require it for entry into public schools.
If accepted, the panel's recommendation would be effective Jan. 1, although pediatricians are free to administer the shots earlier. The panel suggested that the oral vaccine still be used if children are planning to travel to areas of the world where polio outbreaks still occur.
The oral vaccine, which has been widely used since 1965, is made from a live but weakened form of the virus and is believed to provide better immunity against the disease because it results in intestinal immunity, which is necessary in polio epidemic settings.
The Salk vaccine is produced from a killed virus and provides bloodstream immunity, less effective during epidemics. But it is incapable of causing the disease.
"We've come full circle in our efforts to finally eliminate the last remnants of polio in the U.S.," said John Salamone of Oakton, Va., father of a 9-year-old boy who contracted polio in 1991 after receiving the oral vaccine. "Now it's up to key medical groups to encourage physicians and other immunization providers to implement the new . . . schedule." Salamone founded a parents' group to fight for a return to the injectable vaccine.
Until his death at age 86, Sabin steadfastly maintained that his vaccine could not cause polio. "What is the proof?" he asked in a 1983 interview with The Times. "One out of 5 million vaccinations with live vaccine doesn't mean the vaccine causes it. There are other kinds of paralysis that simulate polio that are not polio."
Salk responded in a separate interview. "Cases exist [of polio caused by live virus vaccine] which have been documented, and everyone--all but one man--believes the evidence. It is . . . simply remarkable that he casts doubt about it."
Salk died in 1995 at age 80.
In 1996, the CDC altered its recommended polio vaccine schedule to two injections of the killed virus, followed by two doses of the oral product, with the idea that the first two doses would decrease the risk of contracting the disease from the oral doses.
The change effectively reduced the number of cases in the United States to four in 1997 and only one last year, the agency said. And it hopes that eliminating the oral vaccine entirely will end all cases of vaccine-caused polio.
The new recommendations "will guarantee a polio-free America in the next millennium, and we are proud to be a part of this historic movement toward disease eradication," said David J. Williams, president and chief operating officer of Pasteur Merieux Connaught of Swiftwater, Pa., which manufactures the injectable vaccine.
'Virtual Eradication' of Wild Virus
The company said that it would work with government and medical organizations to implement the new policy.
Doug Petkus, a spokesman for Wyeth Lederle of Radnor, Pa., which makes the oral product, said that the company is proud its product contributed to the "virtual eradication of wild polio virus" and pledged to continue to work on vaccines that would benefit children.
The Sabin product was appealing because it was easier to administer to children. It also was very effective in provoking immunity in people who do not directly receive it but who have contact with people who do--a phenomenon known as "herd" immunity.
This is especially valuable overseas in developing countries, where immunization of children is not as widespread as it is here, and also during epidemics. And the oral vaccine does not require sterile equipment, such as needles, or trained health personnel to administer it.