Governors across a swath of states are beginning to lift coronavirus social-distancing rules.

But documents from the Department of Health and Human Services, obtained by the Center for Public Integrity, show that 300,000-plus people could die of COVID-19 in the absence of such measures.

Florida, where some beaches already reopened and drew crowds, would be hardest hit, with over 23,000 deaths.

Maine, Puerto Rico, West Virginia, and Vermont would also fare poorly in terms of death per capita.

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Officials in at least half a dozen states are moving ahead this week with plans to loosen stay-at-home orders, but health experts warn that the coronavirus could kill hundreds of thousands of people if such restrictions are lifted too early.

Federal officials estimated in early April that more than 300,000 people could die across the US if social distancing measures were ditched immediately at that point, according to Department of Health and Human Services documents obtained by the Center for Public Integrity (CPI).

The documents calculate that coronavirus cases and deaths would double every five-and-a-half days in the absence of containment measures, assuming that one COVID-19 patient infects 2.5 others. They add that 0.5% of symptomatic virus carriers would succumb to the illness, CPI and NPR reported.

In a worst-case scenario, the documents suggest, up to 1.8 million people could die.

"The people that are advocating that we eliminate social distancing right now and that we just completely open up the economy, what they're really advocating for is that every single person in this country become infected with coronavirus," Michael Gunn, a professor of medicine at Duke University, told journalists on Tuesday. "Because that's what's going to happen if we throw things wide open. If you like your grandmother, you might not want to do that."

'If we remove the finger, the spring jumps'

Some states — including Florida, Georgia, Texas, South Carolina, Oklahoma, Tennessee, and others — are already beginning to relax restrictions. In all of those states, angry protesters have flocked to state capitols demanding they be allowed to return to work. President Donald Trump tweeted on Wednesday, "States are safely coming back. Our Country is starting to OPEN FOR BUSINESS again."

However, experts are still urging people to stay at least 6 feet apart from anyone around them to slow the virus' spread and prevent hospitals from becoming overrun.

The HHS documents include a "best guess" calculation of expected deaths as well as four other predictions whose death-toll projections range from 94,000 to 1.8 million. Based on nearly a dozen parameters, including transmission and fatality rates, HHS modeled COVID-19's potential impact in the US and estimated the need for critical medical resources like hospital beds and ventilators, according to NPR and CPI.

As of early April, the "best guess" scenario without continued social-distancing measures would lead one in three Americans to contract the virus. Around 300,000-plus would die. In that case, Florida, where some beaches have already reopened, would see over 23,000 deaths. Maine, Puerto Rico, West Virginia, and Vermont would also be badly affected in terms of death per capita, the article found.

Although the documents don't detail how continuing social distancing could alter the trajectory of the coronavirus, CPI obtained another federal document that said stay-at-home orders could reduce COVID-19's transmission by 75%.

"We have at this moment the finger on the spring. If we remove the finger, the spring jumps. So we will see a lot of cases," Juan Gutierrez, a mathematical biology professor at the University of Texas in San Antonio, told NPR and CPI.

The analysis might still be too 'optimistic'

Some experts say the situation may indeed be worse than the HHS predictions, because the government calculations didn't account for the fact that asymptomatic patients can be highly contagious.

"Their model's way too optimistic. They're getting their analysis wrong," Ashish Jha, director of the Harvard Global Health Institute, told NPR and CPI. He added that many officials are underestimating the coronavirus' death rate and ignoring overwhelmed hospitals' limited capacity.

The White House guidelines about relaxing COVID-19 restrictions involve three 14-day phases that incrementally lift statewide measures for individuals, employers, and large venues.

Phase one continues a ban on non-essential travel and large gatherings but permits restaurants, sports venues, and places of worship to "operate under strict physical distancing protocols." Phase two would start after that, if there is no surge in cases, and allow non-essential travel, schools, and bar operations to resume. Phase three green-lights "public interactions" with physical distancing and "unrestricted staffing of worksites." People would again be able to visit long-term care homes and hospitals.

But the plan requires widespread testing, which the US needs to significantly ramp up, as well as contact tracing, and isolation.

"Reopening the US will be a careful, data-driven, county-by-county approach," Robert Redfield, director of the Centers for Disease Control and Prevention, said in a tweet on April 13.

So far, the US has conducted about 4.1 million coronavirus tests, according to the COVID Tracking Project.

But that capacity must grow to at least 20 million a day by mid-summer in order to fully reopen the economy, according to a report from Harvard University. Meanwhile, governors are still flagging shortages of chemical reagents, nasal swabs, and more.

"I'm concerned that this rush to forget everything we've been through in this last six weeks or eight weeks is gaining momentum that is a bit premature," Thomas Denny, CEO of the Duke Human Vaccine Institute, told journalists. "You can start small and then you watch and be ready to do contact tracing and testing in that area, and you build on it. I'm concerned we're going to find ourselves potentially in a worse shape that we've been through the last six weeks if we go too fast on this."

Correction: An earlier version of this story misattributed a comment made by Michael Gunn to Christopher Woods.