London - Experts are celebrating a major victory for vaccination, with officials expected to announce a key breakthrough in the war against polio.
Scientists will confirm that the second of the three strains of the polio virus has been wiped out.
The eradication of "wild polio virus type 3" – known as "WPV3" – leaves only one polio strain left in circulation. It is only the third virus to be eradicated in history, after smallpox was defeated in 1980 and wild polio virus type 2 (WPV2) in 2015.
Dr Doug Brown, of the British Society for Immunology, said: "The global eradication of WPV3 represents a tremendous step forward in the fight against polio and it means that only type 1 of the wild virus is still circulating and causing infections.