A health expert on Monday warned that coronavirus will 'spread widely, rapidly, terribly and millions could die' if Donald Trump lifts lockdowns in the United States early.

Tom Inglesby, a director at the Johns Hopkins Center for Health Security, tweeted his fears after the president said he will reconsider the nation's social distancing policy within a matter of days.

Inglesby tweeted a thread aimed at 'anyone advising the end of social distancing' .

He wrote: 'COVID would spread widely, rapidly, terribly, could kill potentially millions in the yr ahead with huge social and economic impact across the country.'

The president has indicated he supports a return to normal life.

'America will, again, and soon, be open for business. Very soon,' President Trump said at the daily White House coronavirus briefing Monday.

He added: 'A lot sooner than three or four months that somebody was suggesting. Lot sooner. We cannot let the cure be worse than the problem itself. We're not going to let the cure be worse than the problem.'

As the president talked economics and down played the medical portion, he was surrounded by fewer than usual numbers of the White House Coronavirus Task Force. Attorney General Bill Barr and Dr. Deborah Birx were present.

Dr. Tony Fauci, the nation's foremost expert in infectious diseases, was not. In recent weeks, Dr Fauci has garnered a reputation for repeatedly contradicting Trump's claims about coronavirus.

Tom Inglesby, a director at the John Hopkins Center for Health Security, warned that coronavirus will 'spread widely, rapidly, terribly and millions could die' if lockdowns are lifted

Inglesby, who is listed as specializing in pandemics and infectious diseases, said in his tweets: 'How do we gain time to let hosps get more supplies & prepare for high number of pts? How do we lower the speed of spread of COVID in US? How do we lower odds that ICUs will run out of vents, hospitals run out of space? The answer for now is large scale social distancing.'

He warned: 'To drop all these measures now would be to accept that COVID pts will get sick in extraordinary numbers all over the country, far beyond what the US health care system could bear.'

He also said: 'Many models report that health care systems will be completely overwhelmed/collapse by the peak of cases if major social distancing is not put in place.'

'For now we need to keep production running, doctors offices working, groceries, pharmacies, banks open. It is ok to have science informed dialogue about which businesses need to be closed vs what can stay open in some way if social distancing can be put in place in them', Inglesby wrote.

'But we need to press ahead for now w closed schools, mass telecommuting, no gatherings, strong advisory to stay home unless you need to go out – all are needed to slow this epidemic.'

Other experts have also rushed to condemn lifting lockdowns early.

Dr Scott Gottlieb, a fellow at the American Enterprise Institute and former commissioner of the FDA said that public health had to be prioritized over the economy.

Gottlieb tweeted: 'There's no functioning healthcare with hospitals overwhelmed, no return to work with people terrified of a virus raging uncontrolled. There are two ways to end this. Let a vast swath of people catch covid which is unthinkable, or break the epidemic. We must choose the latter.

'This pathogen brought China to a standstill, with perhaps greater lethality than Spanish Flu. Many middle-aged people are suffering long stays in ICU and survive only after weeks of critical care. Make no mistake about it, this pathogen spares nobody, except thankfully the young.'

Former Barack Obama health official told Politico: 'It is way too early to even consider rolling back any guidelines. With cases and deaths rising by the day, the country must double down, not lighten up, on social distancing and related measures.'

Trump, meanwhile, has complained about the caution brought by health care professionals, saying he told his team they would close the 'entire world.'

'I was telling them, if it was up to the doctors, they would keep it shut down, they would say "let's shut down the entire world."' You can't do that,' he said.

The president argued the nation could watch 'hot spots' were there high levels of infection while opening other parts of the country.

'We're going to be watching very closely the hot spots. We're going to be taking care and watching closely our senior citizens, especially those with a problem or illness. We're going to be watching them very, very closely. And we can do that and have an open economy, have an open country,' he said.

Trump was asked if Fauci agreed with his emphasis on the economy.

'He doesn't not agree,' the president replied.

President Donald Trump said he will reconsider the nation's social distancing policy within a matter of days

President Trump would not promise to listen to advice from Dr. Tony Fauci when it came to ending his 15-day social distancing program

Trump announced a new set of policies on Monday, March 16, meant to stem the spread of the coronavirus, that included closing restaurants and no social gatherings over 10 people.

He said that situation will be reassessed at the 15-day mark, which would be early next week. Some medical experts have warned the United States needs to practice extreme containment measures for several weeks or months to ensure the spread of the virus is stopped.

'At the end of the 15-day period, we'll make a decision as to which way we want to go. Where we want to go. The timing. And essentially, we're referring to the timing of the opening. Essentially, the opening of our country. Because we have it pretty well shut down in order to get rid of this invisible enemy,' he said of the coronavirus.

The United States has had more than 41,000 cases of the virus but Trump said those numbers will start to decrease.

'Obviously, the numbers are going to increase with time. And then they're going to start to decrease. And we are going to be opening our country up for business because our country was meant to be open,' he said.

The area in front of the Welcome to Fabulous Las Vegas sign, where tourists often line up to take photos, is shown empty as most businesses in the area are closed as a result of the statewide shutdown due to the spread of the coronavirus

A man crosses trafficless section of Queens Blvd in the Sunnyside section of Queens, NY, after a 'stay home' order and the closing of all non-essential businesses

Families practice social distancing while waiting in line at West Oakland Middle school in Oakland, California, to pick up 'grab and go' meals during the coronavirus shutdown

People descend down the Bethesda Metro train station escalator at commuter rush hour, as Governor Larry Hogan ordered the shutdown of all bars and eateries in Maryland

A sign announcing the closure of the Koret Playground is seen in Golden Gate Park in California

People walk at safe distances on Venice Beach in California

President Trump has been clear he's worried about the economic affect coming from all the businesses being shuttered because of the pandemic. Numerous states have closed restaurants, gyms, bars, and clubs. The hospitality industry has been hit hard by the pandemic. States like California and New York have advised people to stay home as much as possible.

He argued Monday a bad economy could also cause death.

'You have almost 160 million jobs in this country now, by far the most ever. The number of jobs, almost 160 million, so we can't turn that off and think it's going to be wonderful. There'll be tremendous repercussions. There will be tremendous death from that. You're talking about death. Probably more death from that than anything we're talking about with respect to the virus,' he said.

Some experts have predicted the U.S. could experience up to 20 per cent or 30 per cent unemployment because of the coronavirus.

But the president said it would not be just an economic decision to reopen, promising medical experts would have input.

'We, also, have a large team working on what the next steps will be once the medical community gives a region the okay. Meaning the okay to get going, to get back, let's go to work,' he said.

President Trump has taken up the argument that the cure cannot be worse than the disease, referring to the damage inflicted on the U.S. economy.

Earlier Monday, the president retweeted demands from people to be allowed to go back to work when the 15 days his administration recommended are finished.

U.S. Surgeon General Dr. Jerome Adams warned Monday it get worse.

'This week, it's going to get bad,' Adams told NBC's 'Today Show.' 'We really, really need everyone to stay at home.'

He advised patience. 'We know it's going to be a while before life gets back to normal,' he told CBS 'This Morning.'