President Donald Trump said Monday that more than 1 million Americans had been tested for coronavirus and urged people to continue to follow social distancing measures through April to prevent the virus from spreading.

"Every one of us has a role to play in winning this war. Every citizen, family, and business can make the difference in stopping the virus. This is our shared patriotic duty. Challenging times are ahead for the next 30 days and this is a very vital 30 days," Trump told reporters at the White House.

He referred to the testing number as a milestone.

U.S. health officials are urging Americans to follow stay-at-home orders and other measures to contain the spread of the virus, which originated in China and has infected about three-quarters of a million people around the world.

"If we do things together well – almost perfectly – we could get in the range of 100,000 to 200,000 fatalities," Dr. Deborah Birx, coordinator of the White House's coronavirus task force, told NBC's "Today" show.

Dr. Anthony Fauci, a top U.S. health official, cited those figures on Sunday as a possible outcome, but Birx's assessment appeared to suggest the figures could be a floor rather than a ceiling.