It will be known before the end of the year whether or not there is a safe and effective coronavirus vaccine, the United States' top infectious disease specialist has said.
Dr Anthony Fauci predicted such knowledge could arrive by the end of November or beginning of December.
However, he warned there would not be enough doses to vaccinate everyone before 2021.
His comments come amid reports plans are being made for frontline health staff in the UK to receive a Covid-19 vaccine within weeks.
It will be known before the end of the year whether or not there is a safe and effective coronavirus vaccine, the United States' top infectious disease specialist has said.
Dr Anthony Fauci predicted such knowledge could arrive by the end of November or beginning of December.However, he warned there would not be enough doses to vaccinate everyone before 2021.
His comments come amid reports plans are being made for frontline health staff in the UK to receive a Covid-19 vaccine within weeks.Appearing on the BBC's Andrew Marr Show, Dr Fauci was asked if US President Donald Trump's claims that a Covid-19 vaccine, while not a guarantee, will be coming by the end of the year were true.
Dr Fauci replied: "We will know whether a vaccine is safe and effective by the end of November, the beginning of December.
"The question is, once you have a safe and effective vaccine, or more than one, how can you get it to the people who need it as quickly as possible?
"The amount of doses that will be available in December will not certainly be enough to vaccinate everybody, you'll have to wait several months into 2021." He said healthcare workers will likely be prioritised first for any vaccine, as well as people considered at increased risk of complications.
"The amount of doses that will be available in December will not certainly be enough to vaccinate everybody, you'll have to wait several months into 2021." He said healthcare workers will likely be prioritised first for any vaccine, as well as people considered at increased risk of complications.
Dr Fauci added: "That could start by the end of this year, the beginning of January, February, March of next year.
"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 in to the second or third quarter."
Dr Fauci expressed concern that "anti-science" sentiment could have an effect on vaccine uptake.He told the Andrew Marr Show: "One of the things I'm concerned about in the United States is that part of the anti-science translates maybe into anti-vaccine.
"It would really be a shame if we have a safe and effective vaccine, but a substantial proportion of the people do not want to take the vaccine because they don't trust authority.
"That would really be unfortunate if that's the case."