Which Polio Vaccine to Use

One of the remarkable public health successes in recent decades has been the elimination of polio from North America. This success has been the direct result of widespread use of two polio vaccines. The first vaccine, developed by Dr. Jonas Salk, was made from polio viruses that had been "inactivated" (meaning killed); it produced good levels of immunity, but had to be injected with a needle.

The second vaccine, developed by Dr. Albert Sabin, was made from polio viruses that had been "attenuated" (they were not killed, but so weakened in the laboratory that they weren't believed to be capable of causing polio); this vaccine also produced good levels of immunity, but because it could be given by mouth it became the major polio vaccine used in the U.S., given to children in a series of four doses as part of their routine childhood immunization schedule.

The new polio vaccine schedule
Although the vaccines eliminated polio, every year there were a few cases (perhaps a dozen) in which children developed polio from the weakened but still live virus in the oral polio vaccine. After much debate among vaccine and public health experts, the U.S. Centers for Disease Control recently changed the recommendation for the polio vaccine schedule. Instead of four doses of the oral vaccine, it recommends that the killed vaccine be used for the first two doses and the live vaccine be given for the last two; the objective is to use the first doses of killed vaccine to protect against the very tiny risk of contracting polio from the second two doses of live vaccine. (Various sources, including the New York Times, September 20, 1996)

Comment by Child Health Alert: The controversy that centers around the polio vaccine can be confusing, and it is worth clarifying that both vaccines are effective in preventing polio, and the debate is over the pros and cons of using each one. From one perspective, switching entirely to the killed vaccine would provide good immunity without any risk of a child contracting polio from the vaccine. However, the killed vaccine has to be given as a shot, and many public health experts fear that it will be more difficult to get children to complete their full immunization series for polio and other childhood diseases if more shots are added to a schedule that is already crowded with injections.

Thus, while switching to the injected polio vaccine might eliminate the extremely few cases of polio that result from the oral vaccine, the cost of doing this might be an increase in many vaccine-preventable illnesses because children would be less likely to get their full series of immunizations. So the real issue is balancing efforts to eliminate the tiny risk of any vaccine-related cases of polio against efforts to assure that children are fully immunized against the wide range of childhood diseases.

There is no easy answer to this problem, and the CDC acknowledged the controversy by stating that physicians could still choose to stay with the four doses of oral polio vaccine, could switch to the two-injection/two oral doses, or could switch entirely to four injections. What is critical to understand is that whatever immunization approach is used, no responsible public health expert is suggesting that children avoid receiving their full series of polio immunizations.

This article is provided by Child Health Alert.