Washington — President Trump said on Monday that the coronavirus outbreak could last into the summer, perhaps as long as August, an indication that the widespread nationwide slowdown in response to the virus is just beginning. Mr. Trump also didn't rule out further quarantines or curfews in the future, as he rolled out new 15-day guidelines for everyday American life.

"They think August, it could be July," he said at a press briefing Monday, referring to members of the White House task force. "Could be longer than that. But I've asked that question many, many times."

Mr. Trump also admitted that the country "may be" entering a recession, as financial markets closed out one their worst days in history while the president and his team spoke. The president issued new guidelines for how the country can slow the spread of the virus, suggesting bars and restaurants close in states with evidence of community transition and calling on governors to close schools in areas with evidence of its spread.

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The guidelines say Americans should "avoid eating or drinking in bars, restaurants, and food courts" and to instead use "drive-thru, pickup or delivery options." The government also says Americans should avoid groups larger than 10 people, and calls on people to work and school children at home whenever possible, and avoid discretionary travel.

"We'd much rather be ahead of the curve than behind it, and that's what we are," Mr. Trump said as he unveiled the guidelines in a thinned-out White House briefing room.

Dr. Anthony Fauci clarified these guidelines are for 15 days, not through July or August.

"I think the question that, maybe John asked, 'until July' — the guidelines are a 15-day trial guideline to be reconsidering. It isn't that these guidelines are going to be in effect until July," said Fauci, the nation's top infectious disease official. "What the president was saying was that the trajectory of the outbreak may go until then. Make sure that we don't think that these are solid in stone until July."

The recommendations stop short of urging all restaurants and bars or all schools to close, as an increasing number of governors and mayors are doing. The governors in Ohio and Illinois, for instance, have ordered all bars and restaurants to shutter.

The new guidance, which had been promised by Vice President Mike Pence on Sunday night, also calls for basic things that the administration has been stressing all along, such as washing hands and avoiding touching your face.

"We're calling on every American to do your part," Pence said on Monday.

In announcing the guidance, Dr. Deborah Birx, a leading member of the vice president's Coronavirus Task Force, said the millennial generation will be key in stopping the spread of this virus, as millennials know how to communicate digitally and will generally be able to pull through the virus if infected but can easily transmit it to others.

"They are the core group that will stop this virus," Birx said.

Meanwhile, the Trump administration still can't say how many Americans have been tested for the virus, or how many tests have been administered.

"There is a number. I don't have that number," Admiral Brett Giroir, an assistant secretary at the Department of Health and Human Services, said from the briefing podium.

Despite widespread criticism for the administration's inability to deliver a sufficient number of tests, the president, asked how he grades himself in handling this crisis on a scale of 1 to 10, said, "I'd rate it a 10."