So near and yet so far.

One of the greatest public health achievements of the 20th century was the eradication of smallpox in 1980. A year ago it looked as if the world was on the verge of seeing off polio, which once killed and paralysed hundreds of thousands of children each year.

Most of us in our 60s know one or two contemporaries who survived the last major UK outbreak in the 1950s, prior to the introduction of inoculation in 1955 and remember the fear it once induced. A friend recalled yesterday being told by his mother not to play in a stream in Yoker that she called "the polio burn", after a young neighbour succumbed to the virus. Today many of the survivors are suffering again as a result of post-polio syndrome, which inflicts terrible muscle and joint pain as well as breathing difficulties. In the 21st century, nobody needs to suffer this way. The polio vaccine is safe, cheap, effective and easy to administer.

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Until this week the battle appeared to be all but won, thanks to monumental efforts from individual governments and the World Health Organisation. Even in Nigeria, Afghanistan and Pakistan, which host the remaining small pockets of the virus in the wild, numbers of victims have plummeted. In Pakistan just 56 cases have been reported this year. Hence the logic of the government's "one last heave" approach and the deployment of thousands of health workers and volunteers to pop those salty drops down the throats of every last small child in the country in a three-day blitz.

Then came the shootings. Since Monday at least eight of those who set out on this life-saving mission have lost their own lives, shot at close range in what looks like a co-ordinated attack. One girl, a 17-year old volunteer, had received a number of death threats in recent days. Though the Pakistani Taliban denies involvement, this savagery bears all the hallmarks of a jihadist militant group. What twisted logic, what depraved deluded ravings of medieval-minded mullahs can preach against polio immunisation when they must have seen its lethal consequences in their own communities?

It isn't new. In 2004 clerics in northern Nigeria campaigned against polio vaccines, claiming they were part of the Western plot to sterilise Muslims and prevent their numbers growing. As a result, pilgrims carried the infection to Mecca on the hajj and spread it back to countries where it had been eradicated. (Because there is no non-primate reservoir of the virus, interruption of person to person transmission remains critical.)

In 2007 Maulvi Fazlullah, a firebrand cleric in the Swat Valley in Pakistan, used his private FM radio station to preach against polio vaccinations and girls' schooling. For some of these people, the very fact that the Pakistani government is endorsing the campaign is reason enough to resist it. But this time their ranting has a new twist and their paranoia has perhaps some basis. Their claim that the US runs a spy network under the guise of a vaccine programme is not entirely fanciful. In 2011 in an initiative of mind-boggling arrogance and stupidity, US intelligence used the cover of a dummy vaccination programme in its hunt for Osama bin Laden.

If polio survives to stalk children in the 21st century, those who pulled the triggers and forced the suspension of the immunisation programme this week will be primarily to blame. Let's make that clear. But blame attaches also to the CIA for an ill-conceived ruse that served to politicise and undermine the polio eradication programme at the very moment it was about to succeed.

What now? There is some good news. 2012 is the year in which the disease was finally eradicated in India. Interestingly, one key to the Indian campaign was winning over Muslim clerics in poor communities, who had watched dozens of children die from it. The same now needs to happen in Pakistan.

This fight must go on. We can honour those who died this week for the noble cause of a polio-free world only by finishing the work they began.

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