The Georgia State Patrol and other agencies will take “appropriate action to ensure full compliance — no exceptions,” Kemp said. He did not disclose potential penalties, but he said, “We will do what is necessary if people fail to comply.”

Kemp also closed schools for the rest of the academic year, wiping out proms and field trips, senior nights and graduations and other familiar rituals.

Gov. Brian Kemp on Wednesday said he is preparing a statewide shelter-in-place order across Georgia to try to curb the spread of a coronavirus pandemic, a turnabout after weeks of balking at taking more drastic steps to combat the disease. (Report by Greg Bluestein, Video by Ryon Horne, Photos by Alyssa Pointer and Hyosub Shin)

“At this point, I think it’s the right thing to do,” Kemp said of the shelter-in-place order, announced during a late afternoon news conference in a park outside the state Capitol, where his aides enforced social distancing among the officials and journalists who attended.

“We are taking action to protect our hospitals, help our medical providers and prepare for patient surge,” Kemp said. “This action will ensure uniformity among jurisdictions for Georgians sheltering in place and help families and businesses comply with its provisions.”

Kemp spoke as public health officials prepared another grim update of the coronavirus’ toll in Georgia: 4,748 confirmed cases and 154 deaths as of Wednesday evening. The figures represented 631 new cases and 29 additional fatalities since the previous day.

People practice social-distancing as they listen to Gov. Brian Kemp during a press conference Wednesday, April 1, 2020, at Liberty Plaza, across the street from the Georgia State Capitol building in downtown Atlanta. (ALYSSA POINTER / ALYSSA.POINTER@AJC.COM)

Still, the numbers are lagging behind real-time reports from the hardest-hit parts of Georgia. The Department of Public Health said Dougherty County, the center of the outbreak’s largest cluster in Georgia, had recorded 29 deaths, the most in the state. But Coroner Michael Fowler said Wednesday that deaths now total 37 in Dougherty County, along with 23 others in surrounding communities.

No other county has reported more than 20 deaths.

Before his announcement Wednesday, Kemp had come under pressure to expand earlier orders that closed bars and nightclubs, but not restaurants, and limited the size of many public gatherings. Saying extreme measures would cripple the economy in regions relatively untouched by the virus, Kemp had rejected arguments that a failure to act more boldly would cause a further strain on Georgia’s health care system, resulting in more deaths.

But new information about the virus’ spread, Kemp said Wednesday, was “a game-changer.”

Cases of COVID-19, the disease caused by the coronavirus, now have been confirmed in 139 of Georgia’s 159 counties. Federal health officials issued new warnings about transmission of the virus by people who exhibit no symptoms. And scientific projections, including one from the University of Georgia, suggested the state would see thousands of new cases and hundreds of additional deaths in the next several days.

UGA’s Center for the Ecology of Infectious Diseases said Wednesday its latest computer models showed that known coronavirus cases in Georgia could range between 8,800 and 32,200 by April 29.

The death rate among Georgians with confirmed diagnoses has hovered around 3%. But John Drake, a distinguished research professor at UGA’s school of ecology, said that the rate most likely will lower over time.

In Fulton County alone, emergency management officials expect 10 to 15 deaths a day between April 13 and May 14. In a presentation to county commissioners on Wednesday, officials predicted as many as 600 people would die in Fulton County before the virus is contained.

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Another study, by the University of Washington’s Institute for Health Metrics and Evaluation, predicts about 3,000 deaths in Georgia by the outbreak’s end.

More people would die, researchers say, without broad compliance with strict social-distancing rules.

Kemp made Georgia the 37th state to impose shelter-at-home requirements, joining several other Republican governors who had balked at shutting down their states to curb the virus’ spread. Most of the states without such an order have recorded relatively few coronavirus cases.

Before announcing the new restrictions, Kemp used much of his news conference to cite progress already made under the less-stringent measures he imposed last month.

He said Georgia is rapidly increasing its testing capacity, a move critical to “define the battlefield and help us develop a strategy to win this war.”

And he said most Georgians had followed his recommendations to practice social distancing.

“When hardworking Georgians limit their travel, limit their interaction with others and limit their activities,” he said, “they are buying us more time to get additional hospital beds ready, order supplies, and prepare for more positive cases.”

People wait outside Jerry’s Pawn in order to sell or buy items at the downtown Atlanta pawn shop on Wednesday, April 1, 2020. The shop, located on Decatur Street SE, was only allowing two customers in at a time. (ALYSSA POINTER / ALYSSA.POINTER@AJC.COM)

Despite the progress, Kemp said, additional measures are necessary.

“We are constantly reviewing the data, the modeling and the science,” he said.

He said he learned Tuesday of new data that shows the virus “is now transmitting before people see signs.”

“Those individuals could have been infecting people before they ever felt that,” he said of the symptoms. “We didn’t know that until the last 24 hours.”

Health officials have long known that people who were infected but not showing symptoms were capable of transmitting the virus to others.

But the Centers for Disease Control and Prevention recently changed its guidance on this type of asymptomatic infection, leading to updates in state projections on testing, hospital capacity and virus transmission rates.

Van Wimberly walks to his MRI appointment at Grady Memorial Hospital in Atlanta on Wednesday, April 1, 2020, wearing a respirator mask given to him by his mother. JOHN SPINK/JSPINK@AJC.COM

Kemp’s change of heart on a shelter-in-place requirement drew praise from one of his strongest critics, Emory University’s Dr. Carlos Del Rio.

Last month, Del Rio, executive associate dean for Emory at Grady Memorial Hospital, warned that if Kemp did not “shut down” the state, the result would be “a catastrophe in the health care system.”

Calling Kemp’s action a “courageous decision,” Del Rio wrote Wednesday on Twitter: “This is a very important step that will help us to limit the impact of COVID-19 in the Peach State. It will give us time to shore up our hospitals so they are better prepared.”

Others were a little more measured.

“Better late than never,” said state Rep. Scott Holcomb, D-Atlanta. “Crises demand big and fast responses. Instead, we’ve had nothing but incrementalism. That means it’s going to take longer to move past this.”

Even as he charted the new course, questions remain about the ideological underpinnings of Kemp’s earlier approach. His chief of staff frustrated many local officials over the weekend by criticizing their decisions to close some businesses to curb the virus’ spread as an overreaction.

Kemp praised the “personal choices” by many Georgians to isolate themselves before being ordered to do so.

“It is not going to be the government that is going to solve the problem. It is the community at large.”