This live blog was published March 16. For the latest updates from USA TODAY, click here.

WASHINGTON – In a significant increase in measures to stop the spread of the coronavirus, President Donald Trump on Monday issued guidelines that called for Americans to avoid social gatherings of more than 10 people and to limit discretionary travel.

Though he stopped short of imposing a national quarantine or curfew, Trump said the country may be dealing with a number of restrictions through July or August as a result of the virus. He acknowledged the economy may be heading into a recession.

“If everyone makes this change or these critical changes and sacrifices now, we will rally together as one nation and we will defeat the virus and we’re going to have a big celebration all together,’’ Trump said in the closest he came to displaying levity in a somber news conference that underscored the seriousness of the situation.

Just the previous day, Trump had sounded gleeful over news that the Federal Reserve had cut interest rates to near zero, though that did not stop the stock market from tanking again on Monday.

The new guidelines, which are recommendations and not mandates, call on Americans to avoid social gatherings involving groups of more than 10 for the next 15 days. They also suggest that school-age students take classes from home when possible.

Trump called for governors in states with evidence of community transmission to close schools in affected and surrounding areas. Bars, restaurants, food courts, gyms and other venues where groups of people congregate should also be closed in states with evidence of community transmission.

“Each and every one of us has a critical role to play,” Trump said, surrounded by members of his coronavirus task force.

Among the other guidelines:

-- If someone in your house has testified positive, keep the entire household at home. Do not go to work or school.

-- If you are an older person, stay home and away from other people.

-- If you have a serious underlying health condition, stay home and away from others.

-- Avoid discretionary travel, shopping trips and social visits.

-- Avoid eating or drinking in restaurants bars and food courts. Use drive-through, pickup and delivery options.

-- Do not visit nursing homes or retirement or long-term care facilities unless you are there to provide critical assistance.

-- Practice good hygiene such as washing your hands, especially after touching frequently used items or surfaces. Avoid touching your face.

Earlier Monday, the White House pushed back on news reports that it is considering imposing curfews and a national quarantine in the wake of the spread of the epidemic.

"This is not correct," tweeted Katie Miller, a spokeswoman for Vice President Mike Pence, who is heading the task force.

Trump confirmed he's not ready at this point to impose a national quarantine.

In the morning, markets halted trading for 15 minutes moments after opening when stocks immediately fell more than 7%. When trading resumed the drop continued. For the day, the Dow Jones Industrial Average plunged 2,997 points, its biggest drop of all time, eclipsing the 2,352-point fall it had on Thursday.

There were slivers of light in the darkness – U.S. health officials on Sunday pledged to ramp up testing efforts by the tens of thousands. And testing began on a vaccine.

But the U.S. death toll rose to 85, with more than 4,600 known cases as of Monday afternoon. The global deaths surged past 7,100.

In an attempt to slow the virus, more than 30 states ordered the shuttering of all schools.

Other important headlines on coronavirus:

Most of S.F. Bay Area told to shelter in place

In the most restrictive measure yet by local governments, officials in six San Francisco Bay Area counties on Monday issued a shelter-in-place mandate affecting nearly 7 million people.

The order, effective Tuesday, says residents must stay inside for three weeks and venture out only for necessities. The order affects the counties of San Francisco, Marin, Santa Clara, San Mateo, Alameda and Contra Costa, as well as the city of Berkeley.

People should work from home unless they provide essential services such as public safety, sanitation and health care.

“The most important thing you can do is remain home as much as possible,” San Francisco Mayor London Breed posted on Twitter. “There is no need to rush out for food or supplies, as these stores will remain open.”

Residents can still go outside to perform essential functions, such as obtaining services or supplies for the household, and they're also allowed to go exercise and take pets out as long as they maintain a social distance of at least six feet.

The other three Bay Area counties of Napa, Solano and Sonoma were not included in the order, at least for now.

Some courts in the California, including the Bay Area, are delaying trials and even temporarily closing their doors in hopes of helping prevent the virus from spreading further.

Fitness chains announce closures throughout U.S.

Popular fitness clubs — from Orangetheory, SoulCycle, Gold's Gym and Equinox — announced closures Monday.

Boca Raton, Florida-based Orangetheory announced it was closing its franchise-owned high-intensity training locations nationwide at end of classes Monday, and asking independent owners to follow suit. In a letter, CEO David Long stated a March 31 goal to re-open. Orangetheory Fitness franchisees have opened over 1,300 studios in all 50 U.S. states and over 23 countries, per a news release.

SoulCycle stationary-bike studios announced a closure around the world for its clubs on Monday. Interim CEO Sunder Reddy did specify a re-opening date. Soulcycle has nearly 100 locations, most of them in the United States, according to its website.

Gold's Gym announced on Instagram that the franchise-owned gyms would close nationwide Monday at 8 p.m. through March 31. Gold's Gym has over 400 US locations, according to its website.

In announcing the closure of Equinox Clubs to members on Monday, starting at 8 p.m., chairman Harvey Spevak wrote, "The COVID-19 health crisis is presenting challenges that are unprecedented in our lifetime." Equinox has 106 clubs, according to its website.

Life Time Clubs also announced the closure of all locations Monday. The company has more than 150 locations in 41 markets across the U.S. and Canada, according to its website.

-- Jordan Culver, Bryan Alexander and Bill Keveney

CBS, ABC reporters test positive for coronavirus

Six people at CBS News have tested positive for coronavirus, including a correspondent stationed in Italy, as media organizations fought Monday against the same epidemic they’re charged with covering.

Five employees with the virus work in CBS’ New York offices, where most of its journalists were ordered to stay away as a result.

ABC News said Monday that a journalist who worked on the network’s coverage team of the outbreak in Seattle had tested positive for coronavirus. The person, who works in ABC’s Los Angeles bureau, has been isolated since last week and has suffered only mild symptoms.

The network said it has told its entire Seattle coverage team to stay home and has closed its Los Angeles bureau for a thorough cleaning.

At NBC, an employee who worked on the “Today” show tested positive, forcing the show’s anchors Craig Melvin and Al Roker and others who came into contact with the person to be ordered to isolate in their homes as a result.

-- Associated Press

Kentucky Derby postponed

For the first time in 75 years, the Kentucky Derby will not be a part of the first Saturday in May.

Amid growing concerns about the coronavirus pandemic, Churchill Downs will postpone the Derby from May 2 to Sept. 5, according to a source, the Louisville (Kentucky) Courier Journal reported.

The last time the Kentucky Derby wasn’t held on the first Saturday in May was in 1945, when the government issued a ban on horse racing because of World War II. The ban was lifted on V-E Day (May 8), and the Derby was held on June 9. The only other year the Derby wasn’t held in May was in 1901, when it was raced on April 29.

-- Jason Frakes, Louisville Courier Journal

McDonald's to close seating, play areas

The McDonald's fast-food chain will shut down seating areas at all of its company-owned outlets throughout the U.S., limiting sales to walk-in takeout, drive-thru and delivery service. Play areas will also be closed.

Though the move only currently applies to restaurants McDonald's corporately owns, the company expects many of its franchisees to follow suit. That is likely to mean large swaths of McDonald's restaurants - of which there are roughly 13,800 in the U.S. - will operate as drive-thru only.

"Franchisees are strongly encouraged to adopt similar operations procedures while keeping the needs of their people and communities at the center of their decisions,'' McDonald's said.

-- Charisse Jones

Amtrak to cut Northeast Corridor trains by 60%, cancels Canada routes

Amtrak is cutting its frequency on the Northeast Corridor by 60% of its typical weekday schedules between Boston, New York and Washington Monday in response to plummeting demand due to the coronavirus.

Amtrak said Sunday that its Acela Express and Northeast Regional trains would continue to operate but at significantly lower frequencies. The railroad said in an email to employees last week that bookings had dropped 50% while cancellations had soared 300%.

Canada on Monday closed its borders to non-citizens. The new restriction does not apply to U.S citizens. Still, on Monday Amtrak canceled its Cascades service north of Seattle to Vancouver, British Columbia. Starting Tuesday, Amtrak trains in New York that usually operate to Canada will no longer do so.

-- Curtis Tate

Los Angeles schools, Red Cross to open 60 food centers

The Los Angeles Unified School District, which announced it would shut down for two weeks starting Monday, won't be able to open 40 Family Resource Centers to provide childcare, district Superintendent Austin Beutner said in a statement.

Instead, the district, along with the Red Cross, will open 60 "grab-and-go" food centers that'll be open for three hours on weekdays (7 a.m. until 10 a.m.). Students will be able to take home two meals at a time from the stations.

"At this time, state and local health and public safety officials cannot assure us it will be safe for the children and adults at the Family Centers for us to provide care for children at these sites," Beutner said in his statement, which was posted to social media. He added the district is "deeply disappointed."

The food centers are set to open Wednesday.

-- Jordan Culver

N.Y. college dorms may serve as hospitals

College dormitories, former nursing homes and other buildings could be converted into medical facilities to help treat the wave of coronavirus infections expected to hit New York state's hospital system in coming weeks and months.

Gov. Andrew Cuomo called on local governments to identify existing buildings that could most easily be renovated to handle the thousands of additional beds needed to treat New Yorkers with the illness COVID-19, as well as other unrelated medical conditions.

The plan includes deploying the National Guard as well as partnering with private developers and construction unions to complete the emergency project.

It would create an additional 2,000 beds in Westchester County alone. New York City would need another 5,000 beds and Long Island needs 2,000 beds based on the current rate of infections in New York and prior outbreaks in China, South Korea and Italy, Cuomo said.

Without adding new beds at temporary facilities, the state’s existing hospital capacity cannot handle the projected surge in COVID-19 patients, he said.

“The wave is going to break, and the wave is going to break on the hospital system,” Cuomo said.

-- David Robinson, The Journal News

Actors Idris Elba, Kristofer Hivju have the virus

Actor Idris Elba, known for his role in the HBO series "The Wire'' and his movie portrayal of South African icon Nelson Mandela, revealed on Twitter that he has tested positive for coronavirus.

"I feel OK, I have no symptoms so far but have been isolated since I found out about my possible exposure to the virus," the actor said in a video announcement. "Stay home people and be pragmatic.''

Monday evening, Kristofer Hivju, 41, the actor best known for embodying the renowned warrior (and admirer of Brienne of Tarth) Tormund Giantsbane on Game of Thrones, wrote on an Instagram post from Norway, "Sorry to say that I, today, have tested positive for COVID19, Corona virus."

Last week, fellow actors Tom Hanks and Rita Wilson revealed they have tested positive as well.

Could US see high mortality rate if Americans don't follow guidelines?

The United States will end up with as high a coronavirus mortality rate as Italy without an aggressive response that includes Americans following the federal government’s guidance, Surgeon General Jerome Adams said on “Fox & Friends” Monday.

“When you look at the projections, there's every chance that we could be Italy,” Adams said. Actual mortality rates are difficult to determine because not everyone who becomes infected is tested. But about 7% of Italy's confirmed cases have resulted in fatalities. South Korea, which tested and acted aggressively against the outbreak, has seen a death rate of less than 1%.

“There's every hope that we will be South Korea if people actually listen, if people actually social distance, if people do the basic public health measures that we've all been talking about as doctors all along, such as washing your hands, such as covering your cough, and cleaning surfaces," Adams said.

In Washington state, where the virus' death toll has been heaviest, health officials reported that six more people have perished, bringing the total there to 48. By comparison, 71 deaths have been confirmed nationwide.

King County officials said the latest victims ranged in age from 50 to a woman in her 90s who lived in a nursing home in Redmond. None was identified as being a resident of the Life Care Center in Kirkland, which has been the epicenter of the virus in the state.

Updates from Washington:White House says coronavirus curfews not under consideration

– Maureen Groppe

Seventh TSA officer tests positive

A Transportation Security Administration officer at Atlanta Hartsfield-Jackson International Airport tested positive for the coronavirus, bringing the nationwide total to seven, according to the agency.

On Sunday, TSA said two officers in Florida had tested positive, one at Orlando International Airport and the other at Fort Lauderdale-Hollywood International Airport.

Last week, three TSA officers at Norman Mineta San Jose International Airport tested positive, followed by a fourth one.

-- Curtis Tate

Stocks plunge again

Stocks plunged at the opening bell despite the Federal Reserve's emergency action to cushion the economy from a pandemic that is shutting down global business and travel.

Monday’s 12% drop for the S&P 500 means it has plummeted nearly 30% since setting a record less than a month ago, and it’s at its lowest point since the end of 2018. Losses accelerated in the last half hour of trading after Trump said the economy may be headed for a recession.

“Investors aren’t happy because these rate cuts won’t stimulate the economy in the near term. You can’t stimulate demand if everyone is stuck in their house,” says Shana Sissel, a senior portfolio manager at CLS Investments.

– Jessica Menton

NJ, NY, Conn., Md. tighten rules for restaurants, other businesses

New York, New Jersey and Connecticut will limit all bars and restaurants to takeout and delivery services, part of a series of steps the states are taking collectively and separately to fight the spread of coronavirus. The states will also shut down all casinos, gyms and movie theaters, their governors said in a joint announcement. Grocery stores will remain open.New Jersey Gov. Phil Murphy went further, urging state residents not to leave their homes from 8 p.m. to 5 a.m. daily.

"The #Coronavirus doesn't care about state borders, so this agreement with @GovNedLamont & @GovMurphy will help protect the entire Tri-State Area," New York Gov. Andrew Cuomo tweeted. 'These temporary closures will last as long as is necessary to protect the public health." Maryland, Illinois, Ohio, Massachusetts, Washington state, Indiana and New York City are among places that have ordered bars to close and restaurants to stop dine-in service. Takeout and delivery will still be allowed.

– Ashley Balcerzak, Joseph Spector and Jon Campbell

Schools go dark across most of USA

New York City closed its 1,900 public schools, a difficult decision made by dozens of states and big cities as the coronavirus crisis swept through the nation's educational system. Mayor Bill de Blasio had balked at the move affecting more than 1 million students, in part due to meal plans that keep hundreds of thousands of low-income kids fed. The city was providing "grab and go" breakfast and lunch at all schools.

"We made the painful decision to suspend classes," de Blasio said. "We’re going to begin remote digital learning on Monday, March 23, and we’ll do everything in our power to help our kids through this."

Los Angeles, Houston, San Francisco, Seattle and Washington, D.C., are among a long list of big cities that shuttered their schools. Disadvantaged families that rely the most on schools for stable services, such as meals and access to learning materials, will be some of the most negatively affected, experts said.

“Wide-scale learning loss could be among the biggest impacts coronavirus has on children,” said Betsy Zorio, vice president of U.S. programs at Save the Children, an international children's charity.

– Erin Richards

Coronavirus news: What to know

A roundup of additional important coronavirus news you need to know today:

Curbside voting, a lack of poll workers: How coronavirus is affecting Tuesday's election

'We're not being quarantined. We're being detained.'Americans stuck in Cambodia amid pandemic

What zero rates, sub-1% bond yields mean for your mortgages, student loans and credit cards: Hint, it's not all bad.

Elderly woman close to tears hands a stranger $100, hoping for groceries.Luckily, she found the right person

'You can't Netflix them all day.'Coronavirus closed this school where the kids have special needs.

People are buying guns. It's not just toilet paper people are stocking up on. Related: Here's where you can still buy toilet paper.

Desolate store shelves, empty streets: These 16 eerie images depict coronavirus in America

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More:Ustedes nos hicieron muchas preguntas sobre el coronavirus, nosotros se las respondemos

Vaccine tests begin, mass vaccinations a year away

The first participant in a clinical trial for a vaccine to protect against the new coronavirus received an experimental dose on Monday. The National Institutes of Health is funding the trial, which is taking place at the Kaiser Permanente Washington Health Research Institute in Seattle.

The study’s first participant was an operations manager at a small tech company. Several others were in line for a test that will ultimately give 45 volunteers two doses a month apart. There’s no chance participants could get infected from the shots, because they don’t contain the virus itself, an official said. Public health officials say it will take a year to 18 months to fully validate any potential vaccine.

– Associated Press

Canada closes border, but Americans OK for now

Canadian Prime Minister Justin Trudeau closed the country’s borders to all but Canadians and Americans and asked Canadians to say in their homes as much as possible. Trudeau is self-isolating at home with his wife, who has tested positive for the virus. His edict came as many Canadian "snowbirds" are returning home from winter respites in the southern U.S.

Authorities said everyone entering Canada will undergo screening and be asked to self-isolate for 14 days. Canada has confirmed more than 410 infections and reported at least four deaths.

Iran reports deadliest day; African continent threatened

Iran reported its biggest daily death toll yet, 129, pushing the number of victims to 853, Health Ministry Spokesman Kianoush Jahanpour said. The number of infections rose to 14,991. Still, President Hassan Rouhani sounded an encouraging note, claiming that "we are past the peak of the disease."

In Africa, coronavirus has now been confirmed in at least 30 of 54 countries, officials said. South African President Cyril Ramaphosa declared a "national disaster" and announced severe travel restrictions. "My concern is that we have this ticking time bomb" as the virus spreads through the continent's poor communities, Bruce Bassett, a data scientist at the University of Cape Town, told the Daily Mail.

Disney World officially closes its doors

As Disney lovers waved goodbye to Walt Disney World outside Orlando, Florida, which closed Sunday night in response to the pandemic. The company announced that several park-adjacent hotels, dining and shopping experiences would also shut down.

The additional closures include Disney-owned and -operated locations Downtown Disney in Anaheim, California, and Disney Springs in Orlando, both of which will shut down Tuesday. Non-Disney tenants in those locations "will make decisions on whether to continue or adjust operations," read an announcement from Disney Parks.

"We will continue to monitor the situation and maintain regular contact with the appropriate officials and health experts," the Twitter announcement added. It did not include any projected re-opening dates.

– Hannah Yasharoff

Schools are closed. Does online learning really work?

Thousands of schools across the nation were closed Monday and will remain closed for weeks. Some school districts are trying to cope using online studies. But many students have no access to the Internet at home, and teachers and advocates worry the crisis will worsen the existing education gap for low-income households, even as they take steps to try to accommodate students with paper packets or loans of electronic devices.

In Paterson, New Jersey, where more than a quarter of the city lives below the poverty level, about 22% of households don't own a computer, tablet or smartphone and 36% lack an internet subscription, according to 2019 Census data.

“Whenever possible, we will be using the district’s website and resources like Google Classroom," said school district spokesman Paul Brubaker. "But we will still need to make resources available on paper for many of our students."

– Hannan Adely and Ashley Balcerzak, Bergen Record

Wuhan, once the epicenter, sees normalcy returning

China relaxed travel restrictions in and around Wuhan, where the coronavirus was first detected, and thousands of workers returned to factories now ramping up production, the state-run Xinhua News Agency reported. Chinese health authorities said 12 out of the 16 new confirmed cases across the Chinese mainland on Sunday came from overseas. All travelers entering Beijing from overseas are now required to be quarantined at designated sites for 14 days.

Coronavirus screening website launches in California

A coronavirus screening pilot website for some California counties has been launched by Verily Life Sciences, a sister company of Google. The site – which President Donald Trump had hailed as a nationwide screening site in a press conference that reportedly caught Google off guard – is now live for people in Santa Clara and San Mateo counties. Verily created the website in collaboration with federal, state and local officials. The goal is to take the site statewide. Californians can input their personal health information and then are directed to mobile testing sites for a nasal swab test. They'll get test results within days. Only "high-risk individuals" are initially eligible.

– Nathan Bomey

Health care officials say tests will ramp up nationwide this week

Vice President Mike Pence and other health officials said two factors will allow them to increase testing capacity dramatically in coming days: Some 2,000 labs coming online across the nation to process tests, and tests that can be used for drive-through or walk-up centers.

Admiral Brett P. Giroir, assistant secretary of health at the Department of Health and Human Services, said gear and federal health care workers were being shipping out Monday.

Health officials said they were focusing those tests on two groups: Healthcare workers and first responders, as well as those who are 65 and older with a symptoms of respiratory problems and a fever of at least 99.6 degrees. The officials implored Americans to help prioritize those two groups.

– John Fritze and David Jackson

Map: Which states have coronavirus cases?