The national polio policy, a bitter pill for many Americans to swallow, continues to receive an overwhelming vote of confidence by the Utah Department of Health.
The advantages, local health officials say, far outweigh the known risk: There's a greater chance today of getting polio from the vaccine than of contracting the disease from the actual virus."But the risk is very minimal," said Rick Crankshaw, director of the department's immunization program.
An estimated 19 million doses of oral polio vaccine are administered each year in the United States. For every 2.7 million doses of oral polio vaccine given, one case of vaccine-associated polio may occur.
Of greater risk to the public, Crankshaw cautioned, is the declining immunization levels in Utah. Only 92.4 percent of those who entered school in 1987-88 were adequately immunized; 95.1 percent had been vaccinated for polio. (The estimated national percentage is 95 percent and 97 percent, respectively.)
Less than 60 percent of 2-year-olds received the recommended vaccines, and only 63.3 percent were adequately immunized in 1987 for polio. Some 79.8 percent of daycare center children were found to be adequately immunized against the seven childhood diseases, 85.2 percent for polio.
The state's target immunization level is 95 percent.
With large numbers of individuals remaining unvaccinated, health officials fear the exclusive use of the injectable vaccine. While it carries very little risk to individuals, Crankshaw said it also fails to adequately protect members of society.
"The oral vaccine is recommended because it induces intestinal immunity; it's less likely that an individual would, if exposed to polio, come down with it," he explained.
The oral vaccine is also easier to administer and is less expensive. More importantly, he stressed, an individual who gets the oral vaccine will excrete (in the feces) the live vaccine virus - resulting in the immunization of close contacts, in some cases. For example, a family member who changes diapers or does an infant's laundry could be exposed to the virus. Then the virus acts as a booster dose to those previously immunized. This results in a wider spread immunity.
For this reason, the health department continues to recommend the oral vaccine.
However, parents in private physicians' offices can choose either vaccine for their children.
The oral vaccine, Crankshaw said, should not be given to anyone who has cancer, leukemia, lymphoma or any disease that lowers the body's resistance to infection. It also shouldn't be given to anyone taking a drug that lowers the body's resistance to infection, or to anyone who lives in the same house with someone who has these conditions.
"Doctors should ask or know the circumstances before giving the vaccine," Crankshaw said.
The number of naturally occurring U.S. cases of polio has dropped to zero since 1980 from a peak of 20,000 per year in 1952. Utah hasn't had a case of polio since 1961.
But, Crankshaw warns, the trend could easily reverse itself. "The lower the immunization level gets, the greater the risk is for everyone."
The U.S. polio vaccine policy, periodically reconsidered by various advisory committees, likely won't change until vaccination levels rise.
However, the National Academy of Sciences' Institute of Medicine is optimistic that a new, even less threatening vaccine is on the horizon.
Crankshaw said that within two to five years the federal Food and Drug Administration could approve a vaccine that combines the newly enhanced injectable polio vaccine with the diphtheria-tetanus-pertussis vaccine, which most children already get.
By tacking the polio vaccine onto the first few DTPs routinely given to children - typically at 2 months, 4 months, 6 months and 15 months of age - many of the benefits of both polio vaccines would be realized, Crankshaw said.
Such a schedule, he said, "would reduce or even eliminate cases of vaccine-associated paralysis," and might put an end to the tragic flaw in an otherwise stunning success story in the war against polio.