The US death toll from COVID-19 tops 200,000 on Tuesday, accounting for one-fifth of the global casualties from the pandemic, as experts warned of further increases in infections and mortality as cooler fall weather moves people indoors.

As of Tuesday morning, 200,182 people in the US had died from COVID-19, with 6.87 million infected with the novel coronavirus, according to data compiled by Johns Hopkins University, which registered a global death toll of 966,152.

That means the US toll doubled in four months — in late May the country reported 100,000 deaths from the infection.

"These are not numbers; these are human beings. These are friends and family," Dr Ali H. Mokdad, chief strategy officer of the Population Health Initiative at the University of Washington (UW), told China Daily.

"I'm concerned that we're coming into fall and winter where we'll have more infection and we'll have much more mortality, unfortunately," he said in a video interview.

On Monday, the US Centers for Disease Control and Prevention (CDC) withdrew guidance that had said airborne transmission was thought to be the main way the coronavirus spreads. It said the draft recommendation was "posted in error" on Friday.

Commenting on the sudden reversal, Mokdad said it was confusing and that people may lose trust if the messaging is not consistent and made without explaining why the change was made.

"Potentially (there will be) another 200,000 deaths between now and January, (so) we have to be very careful, since we are moving indoors, because cold weather is coming," he said. "It's better to make sure that we are on the conservative side with our recommendations in that regard."

In its update to global COVID-19 mortality projections last week, UW's Institute for Health Metrics and Evaluation (IHME) predicted that cumulative deaths by Jan 1 would hit 378,320.

The institute cited "steeper than expected declines" in several states as the factors for lowering its estimate of 415,000 deaths by year's end that it had predicted on Sept 10. But it cautioned deaths could surge to more than 3,000 per day by the end of December.

"So far we have been underestimating by a little bit the mortality for several reasons. We assumed that when a state reaches eight deaths per day per million, they will go to a lockdown," Mokdad said. "Unfortunately, we underestimate because we assume that states will do something, and states sometimes don't do (that)."

The IHME said that increasing mask use to 95 percent could save nearly 115,000 lives, reducing the expected number of deaths by 62.7 percent.

Mokdad, a UW professor of health metrics, said that in the US, every state decided to do something different.

"CDC China had a very consistent message and told people exactly what they need to do. Sometimes when people didn't wear a mask, there was enforcement," he said. "We know in the United States when you recommend something and you don't enforce it, sometimes it doesn't work."

He added that the US could have done better by locking down earlier and "making sure we stay locked down until we control the virus, then open up".

US President Donald Trump, who previously admitted to playing down the risk of the virus early on because he did not want to "create a panic", continued to say the US would soon see a light at the end of the tunnel.

"We are rounding the corner on the pandemic, with or without a vaccine ... and we've done a phenomenal job — not just a good job — a phenomenal job," Trump said Monday.

He made similar remarks at a rally Saturday night, claiming that the country was emerging from COVID-19 even without a vaccine.

Asked to comment on the president's rally remarks, Scott Gottlieb, a former Food and Drug Administration commissioner, said that the US could expect "at least one more cycle with this virus heading into the fall and winter".

"If you look at what's happening around the country right now, there's an unmistakable spike in new infections," Gottlieb said Sunday on CBS' Face the Nation.

"There's about 15 states with a positivity rate of 10 percent or higher, which is deeply concerning. There's about 30 states where the Rt — the rate of transfer — is above 1, meaning they have an expanding epidemic," he said.

The situation in the country has prompted serious reckoning from academics.

Charles Silver, a law professor at the University of Texas at Austin, and David A. Hyman, a law professor at Georgetown, said the pandemic was the third great crisis of the 21st century and it has already inflicted a greater toll in lives lost and economic hardship than 9/11 and the 2008 financial collapse combined.

"The federal government was not ready for COVID-19, even though it has dealt with epidemics and pandemics for more than a century," they said in a report titled "COVID-19: A Case Study of Government Failure", which was posted last week on the website of the Cato Institute, a Washington-based libertarian think tank.

The downplaying of the coronavirus, as well as opposition to mask wearing and other precautions, has had real consequences for health and safety, noted Jonathan Rothwell, a nonresident senior fellow with the Brookings Institution, and Christos Makridis, a research professor at Arizona State University.

"But the polarization of the pandemic has had another unfortunate side effect: Exacerbating economic harm," they wrote in an analysis titled "Politics is wrecking America's pandemic response".