Polio could be wiped out in Nigeria thanks to improved vaccine, says study

A recently introduced polio vaccine is four times more effective at protecting children than previous vaccines and has the potential to eradicate type 1 polio in Nigeria if it reaches enough children, according to a study published today in the New England Journal of Medicine.

Nigeria is one of only four countries in the world where polio has yet to be eliminated and 82% of global cases so far this year have been in Nigeria. Polio is highly infectious and it primarily affects children under five years of age. A small minority of infected people develop permanent paralysis, which can be fatal.

The monovalent oral poliovirus vaccine, known as mOPV1, has been used in Nigeria since February 2006 and the number of reported cases of polio in the country fell by 75% between 2006 and 2007.

With each dose of mOPV1 received, a child in Nigeria has a 67% chance of being protected against type 1 paralytic poliomyelitis, according to the new study, which was carried out by researchers from the MRC Centre for Outbreak Analysis and Modelling at Imperial College London, working with international colleagues. The standard trivalent vaccine in the same setting had an efficacy of 16%.

Although the monovalent vaccine is proving very effective, many more children need to be immunised against polio if the virus is to be eliminated in Nigeria, say the researchers. In the North West zone of the country, where the majority of new cases are found, 21% of children report never having received a single dose of the vaccine and a further 55% have received fewer than the recommended four doses.