Sixty-nine children in Nigeria have been partially paralysed after weakened viruses from polio vaccines were inadvertently transmitted to people in unvaccinated regions in the north of the country.
Festus Adu, director of the WHO's polio laboratory in Ibadan, Nigeria, told SciDev.Net that this polio outbreak is only appearing in areas where people are refusing to be vaccinated or where there is not enough oral polio vaccine.
"The best way to overcome the outbreak of vaccine-related polio virus is to increase immunisation coverage, making sure that all children get the vaccine," said Adu, whose lab analyses polio samples before sending them for further tests at the Centers for Disease Control in the United States.
Adu, who is also a member of the Nigerian government's polio eradication committee's expert review, said researchers were preparing vaccine alternatives to combat the outbreak.
Adu said monovalent vaccines (which protect against only one of the three strains) should be used in the areas where the virus is still circulating. But nationwide, the polyvalent vaccine (which protects against all three strains of poliovirus) should be aggressively used and coverage increased, he said.
Many Nigerians are blaming the outbreak on vaccination efforts, an attitude experts fear may ruin previous gains in eradicating polio in the country.
The ongoing outbreak in 18 northern states of Nigeria's 36 states started in 2006 that and was reported only last week in Morbidity and Mortality Weekly Review, a journal published by the US Centers for Disease Control.
Nigeria has the largest number of polio cases, accounting for 61 per cent of global polio cases and 95 per cent of cases in Africa, according to the disease surveillance unit of the WHO.
A government immunisation coordinator working in northern Nigeria, who declined to be named, said a heightened immunisation campaign for children was a necessity to stop the epidemic from spreading.
A wide range of government health officials declined to answer SciDev.Net about whether immunisation was being stepped up, saying it was a political as well as a scientific issue and that they were waiting for a statement from minister of health Adenike Grange.
Most of the anti-immunisation campaigns have been in the predominantly Muslim north of Nigeria, and a number of Muslim clerics have been quoted in the Nigerian media as claiming that vaccines are dangerous and cause sterility or illness.