The coronavirus death toll in the US is a "reflection of a failing national response", a top infectious disease expert has said.

"The actual number is higher because not all deaths have been identified and this is just a horrifying number," Xinhua news agency reported on Saturday citing Tom Frieden, former director of the US Centers for Disease Control and Prevention, as saying.

Comparing the US' death toll and mortality rate with those of Germany and South Korea, Frieden said that "these are lives that have been lost and jobs that have been lost because we haven't had an organized, consistent, coherent federal response".

"It's more people than die from suicide or overdose or homicide or HIV.

"In fact, COVID-19 is on track to be the number three leading cause of death in all of the US for this year," Frieden said.

As of Saturday, the US still remains is the worst-hit country with the world's highest number of cases and deaths at 6,722,699 and 198,509, respectively, according to the Johns Hopkins University.