Geneva  - United Nations agencies and other groups started a polio vaccine campaign Friday which aims to immunize 53 million children in West Africa over the course of the next month.

The vaccination campaign will take place in two rounds and will target eight countries, including Cote d'Ivoire, Ghana and Nigeria.

The large campaign, which has received funding from numerous donors including the Bill and Melinda Gates Foundation, was in response to a polio outbreak last year, which spread from northern Nigeria to six other nearby countries.

Some 162,000 trained medics will deliver 66 million doses of the vaccine in each round, of which 33 million will be directed to Nigeria, the focal point of the campaign.

The campaign is being coordinated by several groups including the World Health Organization and the United Nations' Children's Fund or UNICEF. (dpa)