By ADRIAN SAINZ Associated Press

MEMPHIS, Tenn. (AP) — The number of COVID-19 patients in Tennessee hospitals has hit a grim new record at more than 400, and more than twice that number could need beds in the weeks ahead as the state grapples with a new spike in its coronavirus caseload, Vanderbilt University researchers reported Tuesday.

The rolling weekly caseload of hospitalizations jumped nearly 30% between June 7 and June 13, researchers said, with more people in their 20s and 30s who lack pre-existing medical conditions needing treatment. More 31,000 have now been infected in the state. 

Rises in new coronavirus cases and hospitalizations in recent days have led Memphis and Nashville to delay plans to reopen more businesses and increase capacities for restaurants and retail stores. Health experts also stressed that people should keep wearing face masks in public to reduce the spread of infection. 

"If current transmission trends continue, the state may reach 1,000 concurrent hospitalizations in mid to late July or early August," the Nashville-based university's hospital and medical school said in a news release.

The rise in hospitalizations has not yet put stress on the state's hospital system, said John Graves, associate professor of Health Policy and director of the Center for Health Economic Modeling at Vanderbilt.

Republican Gov. Bill Lee and city and county officials have been easing restrictions on businesses during a gradual reopening of the state's economy in recent weeks, despite concerns that Tennessee could worsen local outbreaks by moving too quickly. 

Nashville, for example, is reopening in four phases, and last week, delayed moving to its third phase due to the increased caseload. 

Meanwhile, Shelby County's health department reported hundreds of new infections on Monday and Tuesday, increasing its caseload to more than 7,090. About 200 of these patients are being treated in Memphis-area hospitals, up from 192 on Friday, according to the city and county's virus task force.

Officials had said Memphis and Shelby County could move on Monday into phase three of their reopening, allowing restaurants and other businesses to expand to 75% capacity, but those plans were delayed due to the "disconcerting" upward trend, county health director Alisa Haushalter said.

"We have hit the pause button so that we don't have to hit the rewind button," Dr. Manoj Jain, a member of the county's COVID-19 task force, said Tuesday.