Vaccines are "long shots" and people should not rely on the swift development of one for Covid-19, the UK government's chief scientific adviser has warned.
A group of Oxford University researchers will begin clinical trials for a coronavirus vaccine next week but Patrick Vallance said expectations need to be tempered.
Writing in The Guardian, Mr Vallance wrote: "All new vaccines that come into development are long shots; only some end up being successful, and the whole process requires experimentation." "Coronavirus will be no different and presents new challenges for vaccine development," he added. "This will take time, and we should be clear it is not a certainty." His warning came as Sarah Gilbert, Professor of Vaccinology at Oxford