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The end is in sight for polio

This 1963 poster featured CDC's national symbol of public health, the

My mother immediately became concerned when, as an active child of three, I suddenly had trouble walking. The doctor came (they made house calls then) and confirmed her worst fear—it was polio. Then he left. There was no effective treatment. All that a doctor could do in 1954 was to deliver the news. 

In 1955, Jonas Salk's polio vaccine was approved for general use. The vaccine was mixture of the three most common polio strains that had been inactivated. Reportedly, it was between 60 and 95 percent effective. While Salk's vaccine was being tested, Albert Sabin and Hilary Koprowski were working on separate live oral vaccines.

Competition between the three men was intense. Sabin and Salk were constantly at odds with each other; Sabin once recommended to a Congressional subcommittee that use of Salk's vaccine should be suspended until a safer version could be produced. And that was before the infamous "Cutter Incident" in which several thousand children were inoculated with a preparation contaminated with live virus.

Eventually, Salk's vaccine was supplanted by Sabin's version of the oral vaccine, which consisted of attenuated virus that had acquired mutations after passage through non-human carriers. A trivalent version of the vaccine was licensed in 1963. The live virus produces excellent immunity in the gut, where polio virus is primarily replicated. A living vaccine has the advantage of spreading within the community (especially where hygiene isn't the greatest) so that it is not necessary to achieve a 100% vaccination rate.

Following the successful global effort to eliminate smallpox from the world, which the World Health Organization certified as successful in 1980, a similar effort, The Global Polio Eradication Initiative, began in 1988. The incidence of polio has since dropped from hundreds of thousands of cases per year to less than 1,000 cases reported in 2011. As of this writing, only 48 cases of polio have been reported worldwide in 2012 and those in only four countries: Nigeria, Chad, Afghanistan and Pakistan. In Africa, attempts at vaccination have been plagued by spurious rumors that the vaccine causes sterility.

Unfortunately, the live polio vaccine can occasionally revert to a virulent strain causing paralysis. This is more likely to happen when recipient is immune deficient, such as an AIDS victim. Soon, health authorities will have an important decision to make, as the only remaining polio will be that which is caused by the oral vaccine. It might be then be time to switch back to the killed vaccine, as has already happened in the U.S., or to cease vaccinations altogether. In the history of this disease, that qualifies as better class of problem than has been faced in the past.

I was lucky. As is often the case with young children, I recovered from polio without obvious impairment. The girl across the street was not so fortunate; I still remember her crutches and withered leg. Soon however, nobody's mother, anywhere, will have to worry about polio. 

Representative Image Caption
This 1963 poster featured CDC's national symbol of public health, the "Wellbee", who was depicted here encouraging the public to receive an oral polio vaccine. (Photo: CDC/ Mary Hilpertshauser)
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