The long journey researchers face in finding a cure for HIV/Aids

When the then US health secretary Margaret Heckler made a forecast in 1984 that a vaccine would soon be developed for HIV, several scientists seated in the packed auditorium “blanched visibly,” according to Randy Shilts’s And the Band Played On.

And they were right: It had taken 105 years after the discovery of the typhoid bacterium to develop a vaccine for typhoid.