On Monday, President Donald Trump noticeably changed his tune about the novel coronavirus.

Trump appeared to be taking the pandemic more seriously, encouraging people to limit social gatherings to less than 10 people, adding that they should avoid bars and restaurants and stop nonessential travel.

"We'd much rather be ahead of the curve than behind it," Trump said at a White House press briefing.

The change in tone from the Trump administration, The New York Times reports, appears to have a connection to a report out Monday from the Imperial College COVID-19 Response Team. The report models out different scenarios of responses to the coronavirus pandemic for the UK and the US.

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'The only viable strategy'

The team included representatives from the World Health Organization Collaborating Centre for Infectious Disease Modelling, the MRC Centre for Global Infectious Disease Analysis, and the Abdul Latif Jameel Institute for Disease and Emergency Analytics via the Imperial College of London.

As part of it, the group suggested that without action to suppress cases, 2.2 million Americans could die as a result of the coronavirus pandemic, along with half a million people in the UK.

The report comes to the conclusion that we might need interventions, like social distancing and closing schools, to last many more months than initially expected to suppress transmission of the disease.

"We therefore conclude that epidemic suppression is the only viable strategy at the current time," the researchers wrote.

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Quarantines and social distancing could reduce the number of cases by half

The researchers modeled a number of different scenarios of how the COVID-19 coronavirus pandemic might play out. In the absence of pharmaceutical treatments or a preventive vaccine for the virus, and without any social distancing measures that could slow its spread, they anticipate 81% of the populations in the UK and US will get infected.

That in turn, could lead to half a million deaths in the UK and 2.2 million in the US.

Under "mitigation" techniques scenario, which combines home isolation of suspect cases, home quarantine of those living in the same household as suspect cases, and social distancing of the elderly and others at most risk of severe disease, the two countries might reduce demand on the healthcare systems by two-thirds and deaths by half.

Even so, the researchers noted, they'd expect the limits of hospital beds to be exceeded by 8-times their capacity. That'd translate to 250,000 deaths in the UK, and 1.1 to 1.2 million in the US.

Those mitigation strategies they said, would likely be in place for three months, with social distancing for those over 70 staying in place a month longer.

The modeling, even with mitigation in place is more extreme than estimates by other experts.

In a February presentation hosted by the American Hospital Association, which represents thousands of hospitals and health systems, one expert projected there could be as many as 96 million cases in the US, 4.8 million hospitalizations, and 480,000 deaths associated with the novel coronavirus.

The American Hospital Association said the webinar reflects the views of the experts who spoke on it, not its own.

The researchers say stronger measures are needed to halt the virus

The dire scenarios in the UK report are why the researchers are prioritizing "suppression," which, like mitigation uses social distancing for the whole population, home isolation for those infected, and household quarantines for those living with someone who has contracted COVID-19. It also might require school and university closures.

The aim would be to stop the virus, which is highly contagious, from infecting more people.

Under the suppression scenario, the social distancing policies would need to be in place for 5 months or longer.

Those tactics would need to be in place on and off until a vaccine becomes available, which could take up to 18 months.

To be sure, following a suppression protocol wouldn't be easy.

"Suppression, while successful to date in China and South Korea, carries with it enormous social and economic costs which may themselves have significant impact on health and well-being in the short and longer-term," the researchers said in the report.