Who developed the polio vaccine announced in 1955?

Jonas Salk, whose killed-virus vaccine was announced on 12 April 1955 to something close to national celebration in the United States - church bells rung, sirens sounded, schools closed. Polio had been paralysing tens of thousands of children a year, and the fear was disproportionate to the numbers precisely because it struck children in summer and nobody knew how.

Salk refused to patent it. Asked on television who owned the patent, he said the people did, and could you patent the sun - which is quoted constantly and was slightly more complicated legally than it sounds, since lawyers had concluded it was probably not patentable anyway. His refusal was still genuine and cost him a fortune.

Albert Sabin's live oral vaccine followed and largely replaced it worldwide, because it was cheaper, needed no needle and spread immunity to contacts - at the cost of very rarely reverting to a form that causes paralysis. The endgame of eradication has therefore had to switch back to the injected vaccine. Polio is now endemic in two countries, and the campaign has been repeatedly set back by attacks on vaccinators after the CIA used a fake vaccination programme as cover during the hunt for Bin Laden.