About 10 times a year, a child or an adult will contract paralytic polio from the very vaccine that prevents it.
In fact, all the cases of polio in America come from the vaccine. The naturally occurring (or wild-type) polio virus hasn't been shown to cause a single case of polio in the United States since 1979.
The problem raises an tough question: Is it ethical for doctors to give a vaccine that they know can occasionally, even rarely, cause a catastrophic disease?
The question is even more complicated because an alternative vaccine is available that carries no risk at all for the individual. At the same time, it is more difficult to administer, and it is not considered as effective from a public health point of view.
Last week, the Institute of Medicine, under contract to the U.S. Public Health Service, convened a committee to review the current use of polio vaccines and decide whether it is time for a change in this country's polio policy.
Few at the meeting predicted any radical changes. "The status quo is very appealing," said conference chairman Dr. Frederick Robbins of Case Western Reserve University in Cleveland.
But concern is on the rise, in part because dozens of lawsuits, with millions of dollars at stake have been brought against Lederle Laboratories of Wayne, N.J., the sole producer of oral polio vaccines in the U.S.
The problem with the polio vaccine is similar to the controversy over the pertussis vaccine, which has been linked to major injuries, forcing a number of manufacturers to stop producing the vaccine because of high liability insurance costs.
In the case of polio, society has so far been willing to pay the price of a few injured lives each year in order to prevent the epidemics that panicked this country in the middle of the century -- epidemics that closed swimming pools, dispersed crowds and struck more than 22,000 Americans every year.
"We have paid a price," Robbins said, "but it has been very small . . ." compared to the benefit of wiping out polio.
At that time, the decision to risk hurting a few to save tens of thousands was sound public health policy. But times have changed. For the public, and even most physicians, the memory of the polio epidemics has dimmed.
Congress has tried to take away some of the sting by passing a no-fault law to compensate those injured by any vaccine made according to federal specifications. In December, Congress finally established funding to support the compensation program. Though the no-fault system has yet to be tested, some predict it will fail because injured parties, unsatisfied with the payments, will sue anyway.
Meanwhile, health officials are looking to technology as a possible solution to the polic vaccine controversy.
The commonly used oral polio vaccine (OPV) is made from a living virus that has been damaged to make it unlikely to cause disease. OPV is easy to use because it is given as a drop of fluid on the tongue, and its ability to spread to other individuals is actually considered a public health benefit since those not reached by vaccination programs -- especially in low-income, inner-city areas -- often get vaccinated anyway through close contact with someone receiving the vaccine.
On those few times that it causes disease, it either directly attacks the vaccinated child, or -- after growing in the child, and sometimes mutating into a more virulent form -- it spreads from the child to an unprotected adult living in the child's household.
Infection by vaccine can be avoided with a newly enhanced and Food and Drug Administration-approved inactivated polio vaccine (IPV) made by Connaught Laboratories Ltd. of Swiftwater, Pa., which will become available in March. Since the virus in the IPV is totally inactivated, it cannot cause disease in the individual.
IPV, however, has to be injected, which is a disadvantage in vaccinating large populations. IPV also requires several inoculations to confer immunity. What's more, because it doesn't spread, it would not provide protection to those not reached by the immunization program.
Worldwide, oral vaccine is used in all but five countries. France, however, has taken a middle road: Doctors and patients may choose which vaccine they want. In the early '70s, the choice was about evenly split; today, one third choose the OPV and about two thirds choose the newer IPV.
Another option is to give IPV first to generate some antibodies that would protect the individual against the small risk of active polio and then follow that with the oral form.
The Institute of Medicine committee must now balance the benefits of using the individually less risky IPV with the chance that such a policy shift could result in an outbreak of wild-type polio if fewer people receive protection against the disease.
A decision is due in a few months.