The Congo Basin. In a campaign to eliminate polio from the world, fourwar-torn African countries have pledged to work together to vaccinate 16 million children overfourdays. On a journey that takes him through the Congo basin in central Africa, George Arney follows health workers up the river and through the jungle as they vaccinate everyone they meet, from slum-dwellers to Pygmies, and asks why this high-profile campaign is proving so controversial in the countries it is trying to help. Producer Dinah Lammiman. Repeated Monday 8.30pm