A coronavirus resurgence is wiping out two months of progress in the US and sending infections to dire new levels across the South and West.

Administrators and health experts are warning that politicians and a tired-of-being-cooped-up public are letting a disaster unfold.

The US recorded a one-day total of 34,700 new COVID-19 cases, the highest level since late April, when the number peaked at 36,400, according to the count kept by Johns Hopkins University.

While newly-confirmed infections have been declining steadily in early hot spots such as New York and New Jersey, several other states set single-day records this week, including Arizona, California, Mississippi, Nevada, Texas and Oklahoma. Some of them also broke hospitalisation records, as did North Carolina and South Carolina.

“People got complacent,” said Dr Marc Boom, CEO of the Houston Methodist hospital system. “And it’s coming back and biting us, quite frankly.”

Stocks slid on Wall Street as the news dampened hopes for a quick economic turnaround. The Dow Jones Industrial Average lost over 700 points for a drop of 2.7%. The broader S&P 500 fell 2.6%.

The virus has been blamed for over 120,000 U.S. deaths — the highest toll in the world — and more than 2.3 million confirmed infections nationwide. On Wednesday, the widely cited University of Washington computer model of the outbreak projected nearly 180,000 deaths by Oct. 1.

California reported over 7,100 new cases. Florida’s single-day count surged to 5,500, a 25% jump from the record set last week.

In Texas, which began lifting its shutdowns on May 1, hospitalizations have doubled and new cases have tripled in two weeks. Gov Greg Abbott told KFDA-TV that the state is facing a ‘massive outbreak’ and might need new local restrictions to preserve hospital space.

The Houston area's intensive care units are nearly full, and two public hospitals are running at capacity, Mayor Sylvester Turner said.

Houston Methodist’s Boom said Texans need to ‘behave perfectly and work together perfectly’ to slow the infection rate.

“When I look at a restaurant or a business where people ... are not following the guidelines, where people are just throwing caution to the wind, it makes me angry.”