LONDON, Oct 25 — US infectious disease expert Anthony Fauci said today it would be clear whether a Covid-19 vaccine was safe and effective by early December, but thatmore widespread vaccination would not be likely until later in 2021.

"We will know whether a vaccine is safe and effective by the end of November, the beginning of December,” Fauci told the BBC.

"When you talk about vaccinating a substantial proportion of the population, so that you can have a significant impact on the dynamics of the outbreak, that very likely will not be until the second or third quarter of the year.” — Reuters