Joe Biden is 77 years old. President Trump is 73 years old. Bernie Sanders is 78 years old and had a heart attack last year.

They are just the kind of Americans that the CDC would consider most at risk amid the coronavirus outbreak. They're also running for president -- or in the case of Trump, re-election.

TRUMP WANTS TO SEND AMERICANS CHECKS 'IMMEDIATELY' IN RESPONSE TO CORONAVIRUS, MNUCHIN SAYS

So as the pandemic has forced the entire country to change its daily habits, so too has it compelled 2020's septuagenarian presidential field to take precautions.

In the Democratic primary race, Biden and Sanders have transitioned essentially to a virtual campaign, for the good of their supporters, their staff and themselves.

Florida, Illinois and Arizona are holding primaries Tuesday, but the rest of the primary calendar remains in limbo as other states postpone. In the meantime, the rapidly spreading coronavirus, which causes COVID-19, has grounded both the former vice president and Vermont senator, leading them to cancel campaign events and shift to relying on virtual rallies and town halls and press briefings from home.

The two candidates -- and especially Trump -- are still probably doing more than the Centers for Disease Control and Prevention and the White House would recommend. The administration on Monday released new guidelines for Americans to curb the spread of COVID-19; one guideline specifically states: “If you are an older person, stay home and away from other people.”

Another states: “If you are a person with a serious underlying health condition that can put you at increased risk (for example, a condition that impairs your lungs or heart function or weakens your immune system), stay home and away from other people.”

During Sunday’s primary debate, Sanders was asked about his heart attack in October, and how he planned to stay safe during the outbreak.

“We had a fireside chat, not a rally,” Sanders said during the debate. “I love doing rallies and we bring many thousands of people out to our rallies. I enjoy it very much. We’re not doing that right now.”

Sanders also said that he did not shake hands with the former vice president at the beginning of the debate and that he is “very careful about the people I am interacting with.”

Biden, in a veiled swipe at Sanders, said later, “fortunately, I don’t have any of the underlying conditions you’re talking about,” adding that he is in “good health.”

Trump, who tested negative for coronavirus over the weekend, has still been holding in-person meetings with the coronavirus task force, executives from pharmaceutical and health care industries, and more. The president held a briefing with reporters in the James S. Brady press briefing room at the White House Tuesday and said he was slated to meet with leaders of the tourism industry later in the day.

Meanwhile, the Biden campaign said the former vice president would spend Tuesday’s primary day in Delaware. It is unclear, at this point, if he will hold any public events. Biden conducted a tele-town hall on Monday into Illinois, Arizona and Florida.

The Sanders campaign said Tuesday they are “not doing traditional GOTV outreach in states holding primary contests today.

“We are making clear to voters that we believe going to the polls amid the coronavirus outbreak is a personal decision and we respect whichever choice they make,” Mike Casca, Bernie 2020 communications director, said in a statement. “We are also passing along guidance from the CDC on staying safe during the crisis.”

SANDERS ATTACKS BIDEN RECORD AS ONE-ON-ONE DEBATE TURNS PERSONAL

Sanders also previously had suggested that the primaries on Tuesday should be postponed for safety reasons amid the coronavirus outbreak.

In a post-debate interview on CNN, Sanders, I-Vt., pointed to the guidelines released by the CDC limiting gatherings for the next eight weeks as the country grapples with the highly contagious COVID-19.

“I would hope that governors listen to the public health experts and what they are saying is…we don’t want gatherings of more than 50 people,” Sanders said when asked about Tuesday’s contests. “I’m thinking about some of the elderly people sitting behind the desks, registering people and doing all that stuff. Does that make sense? I’m not sure it does.”

Ohio later postponed its Tuesday primary, but the other states pressed ahead.

As of Tuesday afternoon, there were more than 5,600 confirmed cases of the novel coronavirus in the United States, with 94 coronavirus-related deaths.

Fox News' Andrew Craft and Paul Steinhauser contributed to this report.