A few drops that let the Western world forget polio

Yesterday's sudden withdrawal of polio vaccine has catapulted the disease from obscurity into the headlines.

Yesterday's sudden withdrawal of polio vaccine has catapulted the disease from obscurity into the headlines.

Hardly anyone in Britain under the age of 45 knows anything about polio, because in 1955 vaccination against the paralysing virus was introduced and within five years it virtually disappeared. But before this, polio struck fear into families.

When the vaccine came along, it was eradicated in the developed world almost overnight. In the UK, there were only 28 confirmed cases between 1985 and 1994.

Unfortunately, the latest scare is likely to create a new kind of worry in the minds of parents. Although the Department of Health is adamant that the risk of catching BSE from the withdrawn polio vaccine is infinitesimally small, any bad publicity about vaccines is bound to put people off the idea of all vaccinations.

The irony is that most of the recent cases of polio in the Western world (19 of the 28 British cases and 124 of the 133 American cases) have been caused, not prevented, by the very vaccine designed to prevent the disease. How can this happen?

The first polio vaccine consisted of killed polio organisms. A series of three or four injections provided full protection, with no risk of causing the disease. A few years later, in 1961, a new "live" vaccine was developed. This vaccine contained living polio viruses, and it could be given by mouth. Although it carried a theoretical risk of inducing polio as a disease, this was such a remote possibility that by the mid-Sixties it was a first-line vaccine against polio. Its success has been astounding. In the UK, there has not been a single confirmed case of indigenous (not imported from abroad) "wild-type" polio for more than a decade.

But even in countries with vaccination programmes, there have remained a stubborn few cases of polio. Most of them were caused by the "live attenuated" virus contained in the oral vaccine.

In America last year, it was recommended that children be immunised with the original "killed" vaccine. France and Germany have moved away from the live vaccine.

Although there is honest disagreement among British experts about the best way forward, there is huge agreement that immunisation of British children against polio remains essential until polio joins smallpox in the archives of history.

Dr Fred Kavalier is a practising GP in north London