the polio vaccine administered at present may be unsafe. There is a controversy brewing over its potency. Experts in India say that the monovalent oral vaccine (mopv1) is being used without assessing its safety. It was introduced in the country in 2005 after it was given a fast track licence by the drug controller general on the premise that the same vaccine was used in the 1960s. Before 2005, the trivalent vaccine was in use.

A paper published in The Lancet says the vaccine is five times more potent than the one developed in 60s. The paper is authored by Nicholas Grassly of London's Imperial College and co-authors include experts from who and the National Polio Surveillance Project in India who are part of India Expert Advisory Group (ieag). The polio programme is implemented by the government under directions from who's Global Polio Eradication Initiative. ieag has experts from international agencies, including who, take decisions on vaccines. The study has drawn sharp reactions from Indian scientists. They say that ieag misled them into believing that mopv1 was the same vaccine that was used in the 60s without being told of its higher potency. They are concerned because the increased potency could lead to further adverse impacts. There is evidence to show that oral polio vaccine can increase the incidence of non-polio related paralysis.

"No informed consent was taken, nor was the public told that the vaccine was experimental,' wrote Jacob Puliyel of St Stephens Hospital, C Sathyamala of Council for Social Development and D Banerji of Centre for Social Medicine and Community Health, Jawaharlal Nehru University, in response to the study. Replying to their concerns, Grassly along with the co-authors said they had not misled and that the vaccine was approved by the drugs controller general. Grassly feels that there is little cause for concern on adverse impacts of mopv1 because it has the same potency as the trivalent vaccine, while accepting that the monovalent vaccine of 1960s was of lower potency.