Coronavirus vaccine could be ready as early as end of 2020, Dr Fauci says

'I believe it will be when and not if'

A coronavirus vaccine could be ready as early as the end of 2020 or early 2021, according to White House coronavirus taskforce adviser Dr Anthony Fauci.

The government's top infectious disease expert testified at a House committee on Tuesday that he believes "it will be when and not if" a vaccine for Covid-19 would be available.

Dr Fauci's outlook on a vaccine came as the number of coronavirus-related deaths in the US fell for the fourth consecutive day.

"We feel cautiously optimistic, based on the concerted effort and the fact we are taking financial risks -- not risks to safety, not risks to the integrity of the science, but financial risk to be able to be ahead of the game -- so that when, and I believe it will be when and not if, we get favourable candidates with good results, we will be able to make them available to the American public," Dr Fauci testified Tuesday.

"It would put us at the end of this calendar year and the beginning of 2021."

The World Health Organisation on Tuesday reported that the United State's daily death toll has been declining over the past four days, from 770 on Friday to 733 on Saturday and 690 on Sunday. There were 558 on Monday and 308 deaths on Tuesday.

The downward trend in US coronavirus deaths came as Dr Fauci testified to the House Energy and Commerce Committee alongside FDA commissioner Stephen Hahn, Centres for Disease Control and Prevention Director Robert Redfield, and Assistant Secretary for Health Brett Giroir.

They testified that Donald Trump has not asked them to slow down testing after the president said during his Tulsa rally that the White House coronavirus task force was told to slow down testing because it was uncovering too many infections.

"None of us have ever been told to slow down on testing. ... In fact, we will be doing more testing," Dr Fauci said.

While the White House has said the comment to slow down testing was a joke, Mr Trump told reporters that he was serious about his that he'd directed the taskforce to slow down testing.

The US has so far tested 27 million people with about 8.4 per cent, or about 2.3 million people, testing positive.

Dr Fauci said the country's response has been a "mixed bag", with hard-hit places like New York City successful at mitigating the spread but other areas seeing a disturbing surge of infections.

"Right now the next couple of weeks are going to be critical in our ability to address those surges we are seeing in Florida, Texas, Arizona, and other states," Dr Fauci said. "They are not the only ones having difficulty. Bottom line, it is a mixed bag."

In his prepared remarks, the director of the National Institute of Allergy and Infectious Diseases told the committee that the progress on the US's vaccine efforts would be critical to bringing the pandemic to an end.

"If you look at the history of viral diseases, it is generally vaccines that put the nail in the coffin of these types," Dr Fauci said.

He added: "The rigorous clinical testing required to establish vaccine safety and efficacy means that it might take some time for a licensed Sars-CoV-2 vaccine to be available to the general public."