Anthony Fauci Matthew McConaughey
Dr Anthony Fauci explained to Matthew McConaughey on Thursday that the death toll would be 'enormous' had the US attempted to achieve herd immunity.

In a discussion with the actor on Instagram, the nation's top infectious disease expert said: 'If everyone contracted it, even with the relatively high percentage of people who are without symptoms... a lot of people are going to die.'

'If you look at the United States of America with our epidemic of obesity as it were, with the number of people with hypertension, with the number of people with diabetes, if everyone got infected the death toll would be enormous and totally unacceptable,' Fauci said.

'And that's the reason why we are against saying "let if fly, let everybody get infected and we'll be fine" that's a bad idea,' Fauci, who is the director of the National Institute of Allergy and Infectious Diseases, added.

His comments come hours after the Centers for Disease Control and Prevention (CDC) released a grim forecast that predicts 189,000 Americans could die from COVID-19 by September 5.

'This week's national ensemble forecast predicts that 4,200 to 10,600 new COVID-19 deaths will be reported during the week ending September 5 and that 180,000 to 200,000 total COVID-19 deaths will be reported by that date,' the agency's website reads.

The CDC also said that 'state- and territory-level ensemble forecasts predict that the number of reported new deaths per week may increase over the next four weeks in Colorado and may decrease in Arizona, the Northern Mariana Islands, Vermont, and Wyoming'.

Previously, the ensemble forecast that was published on August 6 predicted that about 181,000 people in the US could die by August 29.

So far, at least 167,071 Americans have died from COVID-19. The US is also reporting the highest number of cases globally with more than 5.2 million.

Washington has invested more than $10billion in six vaccine projects and signed contracts guaranteeing the delivery of hundreds of millions of doses should they be approved following clinical trials.

If a COVID-19 vaccine is proven effective, the US will ensure it's distributed for free to all Americans, officials said Thursday.

The vaccine doses themselves will be paid for by the government.

Francis Collins, director of the National Institutes of Health (NIH), said he was 'cautiously optimistic' that at least one of the six vaccines the US had invested in would come through by the end of the year.

Critics of President Donald Trump have expressed worries that the administration may bypass safety precautions to announce a vaccine is available before the election on November 3 - a charge Paul Mango, a senior health department official, denied.

'We are not at all reducing the regulatory rigor with which we will evaluate and hopefully approve vaccines,' he said, adding that the US 'is on track to deliver hundreds of millions of doses by January 2021'.

Russia this week approved a vaccine even before the start of the last phase of clinical trials, in which the drug is injected into tens of thousands of volunteers to verify its effectiveness and safety.

'I hope that the Russians have actually definitively proven that the vaccine is safe and effective, but I seriously doubt that they've done that,' Fauci said at a virtual panel hosted by National Geographic.

The speed at which Russia is moving to roll out its vaccine highlights its determination to win the global race for an effective product, but has stirred concerns that it may be putting national prestige before sound science and safety.