Oral polio vaccines have not yet covered West Africa: survey of immunization coverage conducted in Niger.

Following the re-emergence of polio in West Africa, an investigation was conducted on the occasion when transients gather for the festival in Niger, where the oral polio vaccine (OPV) and BCG coverage among children under the age of 5 years can be evaluated. A total of 259 children were investigated, including 186 from settled families and 73 from unsettled families. OPV coverage was found to be as low as 32.4%, and 61.8% of all participants in the study had not received both OPV and BCG. There were more children who had not received the OPV in unsettled families than in settled families. As there are still unvaccinated children in Niger, polio continues to occur among them. Moreover, outbreaks can transfer to more densely-populated areas, causing much larger outbreaks. To stop the chain of transmission, it is essential to reconsider the strategy of mass vaccination in order to cover all children thoroughly, including transients.