London,  Holding the Tokyo Olympics any time before a vaccine is found will be "very unrealistic," according to a leading global health expert. Professor Devi Sridhar said that the development of the vaccine will be key to when the Olympics can be held.

Sridhar, however, said that the vaccine could be found earlier than what was expected. "We're hearing from the scientists that this could be possible. I had thought it would be a year or a year and a half away but we're hearing possibly this could come sooner," she told BBC Sport.

"If we do get a vaccine within the next year then actually I think that (Olympics) is realistic. The vaccine will be the game-changer -- an effective, affordable, available vaccine.

"If we don't get a scientific breakthrough, then I think that looks very unrealistic." Sridhar, however, said that the International Olympic Committee (IOC) and the Tokyo 2020 organisers made the right decision in postponing the Games by a year.

"I think they've made the right decision in saying 'we are going to put it back a year and re-evaluate'," she said.

Originally supposed to be held from July 24 to August 9, 2020 the Olympics had to be postponed to July 23 to August 8, 2021 due to the coronavirus pandemic and rising pressure on the IOC from a number of quarters.