The United States registered its 200,000th death from the Covid-19 pandemic on Tuesday, the latest grim milestone for the country just weeks before voters decide if President Donald Trump will stay in office.

According to a rolling tally by Johns Hopkins University, 200,005 Americans have died and 6.86 million have been confirmed infected by the novel coronavirus.

The US has had the world's highest official death count for months, ahead of Brazil and India, with 137,272 and 88,935 deaths respectively.

Overall, the US accounts for four percent of the world's population and 20 percent of its recorded coronavirus deaths.

Critics say the statistics expose the Trump administration's failure to meet its sternest test ahead of the November 3 election.

"Due to Donald Trump's lies and incompetence in the past six months, (we) have seen one of the gravest losses of American life in history," his Democratic rival Joe Biden said Monday.

"With this crisis that required serious presidential leadership, he just wasn't up to it. He froze... and America has paid the worst price of any nation in the world."

While insisting that the United States is already "rounding the corner," Trump has high hopes that the swift approval of a Covid-19 vaccine will boost his reelection chances.

"We will distribute a vaccine, we will defeat the virus, we will end the pandemic, and we will enter a new era of unprecedented prosperity, cooperation, and peace," Trump said in a recorded message to the UN General Assembly on Tuesday.

Trump has previously stated that by April of next year, most Americans who want to be immunized will have a vaccine.

But most experts argue that betting on vaccines is not a viable strategy.

"Failed national response"

Without adhering to masks, distancing and contact-tracing, and without ramping up testing, tens of thousands more could still die before life returns to normal in the US.

"Covid will be the third leading cause of death this year in the US," tweeted Tom Frieden, the director of the Centers for Disease Control and Prevention (CDC) under former President Barack Obama.

"The staggering death toll from the virus is a reflection of a failed national response, but it's not too late to turn it around."

Only the number of people who died from heart disease and cancer will be higher.

The US likely crossed 200,000 deaths in July, said Eric Topol, director of the Scripps Research Institute, citing the excess overall mortality rate.

The initial lack of tests led to an undercount of the virus's count.

"We are the outlier to have been caught flat-footed with no testing, and just not learning from mistakes," Topol said.

"We never got adequate suppression, and yet we're opening everything and trying to make believe that everything is just great."

The adoption of public health measures remains mixed across the US.

In many cities, students have gone back to school virtually, the indoor areas of bars and restaurants remain closed, and mask use is up.

But hotspots are still flaring up, currently in the Midwest and on college campuses that returned to in-person learning.

Critics say Trump abdicated responsibility and left it to the state governors to deal with the crisis and decide on lockdowns.

"We had a crazy quilt of responses across the country that confused the average person," William Schaffner, a health policy professor at Vanderbilt University, told AFP.

"We needed a unified, coherent, strong, national response."

The US health system will be further tested this winter, said Harvard epidemiologist Michael Mina.

Anticipating a "twindemic" of coronavirus and flu, officials are stocking up on a record number of flu vaccines.