People spend their Sunday afternoon on the National Mall in Washington D.C., the United States, on June 28, 2020. (Photo by Ting Shen/Xinhua)

"It is increasingly clear that many governors reopened their states too quickly, reigniting the virus and hurting their economies," wrote Mark Zandi, chief economist of Moody's Analytics.

WASHINGTON, June 29 -- The resurgence of COVID-19 cases across the United States is threatening to derail the nascent economic recovery as many states have either paused or partially reversed their staged re-openings, economists and officials have warned.

"Economic activity in states with the most significant increases in cases in recent days, including Arizona, California, Florida and Texas, appears to be rolling over," Mark Zandi, chief economist of Moody's Analytics, wrote Monday in an analysis.

"It is increasingly clear that many governors reopened their states too quickly, reigniting the virus and hurting their economies," Zandi wrote, adding containing the virus and supporting the economy are not mutually exclusive.

The bulk of the increase in U.S. COVID-19 infections has been in the South and West, with California, Arizona, Texas, Florida, Georgia and the Carolinas accounting for the bulk of the increase, according to Wells Fargo Securities Economics Group.

"Some increase in COVID-19 cases was expected as the economy reopened and testing continued to ramp up. The rise in infections, however, has been greater than can be explained by testing alone," the Economics Group wrote Friday in a report, noting many states and metro areas have either paused or partially reversed their staged re-openings, which will weigh on economic growth this summer.

U.S. Secretary of Health and Human Services Alex Azar said on Sunday that the "window is closing" for the country to curb the surge of COVID-19 cases, while New York Governor Andrew Cuomo blamed the case increases on a failure to act earlier.