WASHINGTON - Anthony Fauci celebrates a big birthday on Christmas Eve. He’ll be 80. He says he has worked every day since January, often late into the night, laser-focused on fighting the coronavirus pandemic. He enters his ninth decade with remarkable vigor, and attributes his youthful appearance to genetics. His father lived to 97 and never looked his age.

To deal with the demands of his job, Fauci says he relies on the muscle memory from his days as a young doctor working crazy shifts in a big New York City hospital, often all through the night, triaging patients with life-threatening injuries.

"There is no option to get tired. There is no option to sit down and say 'I'm sorry, I've had enough,' " he said. When fatigued, he recalled, he would tell himself: "I'm gonna dig deep and just suck it up."

Which is kind of what he's been advising the whole country.

This hideous pandemic will not last forever, but it won't end soon enough, sadly, for thousands of families who will suffer through the dark days of winter as this cold-weather surge of infections, hospitalizations and deaths hits its peak. Coronavirus vaccines, a marvel of human ingenuity, will not begin to quash the pandemic for many weeks or months.

So: Wear a mask. Keep your distance. Wash your hands. Avoid crowds. Outside is better than inside. Fauci delivers that mantra every time he gives an interview, which is many times a day. He repeatedly cites scientific evidence or the lack of it. He is not hesitant to say that there are things we still don't understand about this virus. And he has issued warning after warning: Take this thing seriously. It's dangerous. We have to stay vigilant. And he says it again and again.

Paradoxically, this grim talk can be soothing, in part because of the way he delivers it: He doesn't emanate fear. Disinformation, bunk and ideologically driven magical thinking have so thoroughly contaminated our information streams that people are desperate to find a safe harbor where two plus two is still four. That makes Fauci a national resource: His currency is trustworthiness.

That's why Fauci got vaccinated Tuesday on a stage at the National Institutes of Health."I feel extreme confidence in the safety and the efficacy of this vaccine," he said, urging people to get vaccinated so there is a "veil of protection over this country that would end this pandemic."

Not everyone loves him or even likes him. He's been derided by critics as apocalyptic. The criticism at times has been venomous, and scary. The fact that Fauci and his wife, Christine Grady - the chief of the bioethics department at NIH Clinical Center - require constant security is one of the countless dismal elements of this wretched, wrenching year. Even their three adult daughters have received harassing messages.

"On the one hand, I'm being adulated as this, you know, iconic figure, this person that everyone recognizes now, and knows. Which is fine. I can't be distracted by that," he said in an interview. "On the other hand, people have threatened my life and have harassed my wife and children and are still doing that. Public health measures have been swept up into the divisiveness of our society," he said.

The only way Fauci gets through is by focusing on his job, he said - which includes speaking clearly to the public about the virus, the vaccines and what science does and doesn't know.

But when he reflects on 2020 he's amazed.

"I could not have possibly made up a year as complicated as this," he said.

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he pandemic will compromise Fauci's Christmas Eve celebration. For nearly half a century he has marked the event with a traditional Italian meal at the home of his sister in Alexandria, Va. Not this year. Fauci will stay home in Washington with his wife.

Another family Christmas tradition has already happened, just a few days ago. Every holiday season Fauci makes timpano at some point when his kids are home. Timpano is an Italian pasta cake, filled with cheese, eggs, meatballs and salami - a caloric atomic bomb - made famous in the 1996 movie "The Big Night." Fauci got the idea from the movie. It's a major production. Ali Fauci, his youngest daughter, now a software engineer in San Francisco, says the greatest part of the timpano is not the food itself, although it's delicious. It's the delight her father takes in preparing it and presenting it triumphantly.

This year he made it while a documentary camera crew captured the moment and his daughters, who are scattered across the country, watched remotely.

"It turned out perfectly," Fauci said. "The pressure was really on. If I had messed it up and it had fallen apart out of the pot it would have been very embarrassing."

Fauci has been warning people that this is no time to mix households. In a recent call among Fauci, Grady and their daughters, Fauci expressed concern that it might look hypocritical if anyone in the family traveled home for the holidays. Before he could even complete a full sentence, the kids said, "We get it, Dad." So the Fauci family will have a Zoom Christmas.

The kids didn't come home for Thanksgiving, either. Fauci and his wife ordered takeout from Cafe Milano, a Washington restaurant popular among the city's power brokers, and shared it with their security detail.

"I felt sad," he said of Thanksgiving. "It was very 2020."

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This is not Fauci's first pandemic. He dealt with the original SARS, H1N1 (the pandemic influenza of 2009 that turned out to be less lethal than feared), MERS - a deadly respiratory virus - and Ebola. The biggest thread in his career has been his work on HIV. Buteven with his long history of fighting new infectious diseases, Fauci has found himself surprised and mystified by the novel coronavirus.

"I have never really seen anything like this. And it still puzzles me," he said.

The virus can cause a fatal disease - but it often causes no symptoms at all.

Whatexplains the wildly unpredictable nature of the virus?

"I don't know," he said. "And that's what I really want to find out."

Fauci said he focuses "like a laser beam" on doing just that and telling the public what he knows - and what he doesn't. But his blunt assessments have not always been well-received. Fauci's grave warnings about the coronavirus - in White House task force meetings he tended to be "the skunk at the picnic," he said - have put him in conflict with President Donald Trump. Fauci remembers Trump asking why he couldn't be more positive about the virus. Fauci said he responded: "I'm trying to give a correct interpretation of what's going on."

Fauci maintains that he and the president remained cordial this year, even after the president insinuated that he might fire him. Fauci certainly heard Trump when, in an October call with campaign staff, the president said of public health officials, "People are tired of hearing Fauci and all these idiots" and pointedly remarked, "Fauci is a disaster." The next day Trump mocked Fauci's botched ceremonial first pitch on Opening Day at Nationals Park.

When he next saw Trump, Fauci said, the president was friendly. Fauci cites a similar origin: Fauci is from Brooklyn, Trump from Queens.

"We've kind of had a little bit of a New York bond, if you want to call it that," Fauci said.

Fauci says he does not enjoy the way the news media keeps pitting him against Trump in stories.But he is unwilling to tell people something that isn't true simply because that's what they want to hear.

"When [Trump] started to say things that were outright incorrect, I could not just stand there and shake my head and say it's OK. I had to go to the microphone," Fauci said. "I didn't intend to be anti-Trump. You know? I maintained my apolitical position. But I couldn't stand there and not say anything and being complicit in things that were completely untrue."

The White House did not respond to a request for comment.

In an interview with Fox News's Sean Hannity in July, Trump said, "Dr. Fauci is a nice man, but he's made a lot of mistakes."

Trump and other critics of Fauci point out that, early in the pandemic,Fauci did not recommend that people wear masks to prevent the spread of the coronavirus. Fauci says that was based, in part, on a concern that people would hoard masks needed by health-care workers. Moreover, he said, health officials didn't then know the virus could be spread by people who were asymptomatic. When new information arose, Fauci changed his mind.

"I guess you can call it a mistake. Or is it really a mistake? Or was it really just something you said based on available data?" he asked.

He also changed his mind about in-person schooling. He'd warned of the dangers to children and their ability to spread it to adults - at one pont engaging in a testy exchange with Sen. Rand Paul, R-Ky. - but research showed children rarely get seriously ill from the coronavirus and in-person schooling is not a major source of community spread. This fall, Fauci began pushing a new mantra: Close the bars and keep schools open.

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While the coronavirus has made Fauci a household name, HIV changed his career.

Fauci joined NIH in 1972 and quickly became a rising star, spending nearly a decade treating and curing patients suffering from a wide variety of diseases. Then came HIV. He remembers seeing a June 1981 report by the Centers for Disease Control and Prevention on a new virus infecting five young men in Los Angeles.

A month later, the number of patients with this mysterious ailment had jumped to 26. Soon, Fauci decided to devote his research to what some people initially referred to as Gay-Related Immunodeficiency Disease.

"Oh my goodness, this is a new disease," he realized. And so he dedicated himself to studying it. It was an enticing challenge for an ambitious scientist, but it carried an emotional burden. In the early days of HIV, he could offer his patients no hope of a cure.

"I got prematurely very well known, and was on a skyrocketing type of career, when I made this extraordinary decision that I was going to stop it," he said. "It went from bright sunlight to darkness, because virtually everyone died."

Three years later he was offered the leadership of the National Institute of Allergy and Infectious Diseases. And there he stayed. He has worked in the same office at the same desk he inherited from his predecessor. The couch where visitors perch has become decrepit over the decades. He has an ungainly tropical plant that appears to be immortal and is inhibited with bungee cords.

He could have moved higher in the government. Presidents offered him the top spot at NIH and he declined. He could have become a university president, or gone into the private sector and made big money. But he wanted to stick with what he was good at, and more importantly, what he really cared about, which is fighting emergent diseases.

"I was afraid that if I took something at a higher level it would distance me one step beyond where I wanted to be from my area of expertise and my area of excitement," he said. His message for others: "Stick with your passion. Stick with the thing that intensively interests you."

Among his many professional accomplishments is the creation of a basic research program that contributed to the development of mRNA vaccines like the coronavirus shots from Pfizer-BioNTech and Moderna, which are now being administered in the U.S. And he helped establish PEPFAR - President George W. Bush's program to distribute HIV drugs in developing countries, which Fauci says has saved 14 million lives to date.

During the Ebola outbreak of 2014, Ebola patients were brought to NIH's clinical center for treatment. Fauci treated them directly - "at the bedside with the sickest people in the world," NIH director Francis Collins said.

Fauci knew that Ebola patients, even when fully recovered, would likely be stigmatized or shunned. So when nurse Nina Pham, cured of Ebola, was discharged from NIH and walked out into the sunlight amid a swarm of cameras, Fauci gave her a public hug.

Some of the biggest moments in Fauci's personal life have also taken place at NIH. In 1984, Grady was a new nurse at NIH and could speak Portuguese after working in Brazil. Fauci was treating a Brazilian politician who had a leg injury and wanted to return to his home country. Fauci said he would discharge the patient only if he promised to stay home and keep his leg elevated.

The politician told Grady, who interpreted, that there was no way he'd do what Fauci wanted, because he wanted to go to the beach and to parties. Grady translated that as, "I'll do as you say, doctor."

When he later asked her to visit his office, she feared she was in trouble. Fauci asked her to dinner.

"It was sort of love at first sight," he said.

She moved into Fauci's house a couple of months later and the couple has been there since. They are runners, or were until age caught up with them. They now power-walk along the Potomac River.

They ran two marathons together, stride for stride - almost. She doesn't mention what happened at the end of the first marathon, but Fauci does: Right before the finish line, she said, "See you later" and sprinted ahead to beat him.

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As Fauci turns 80, the country is in the midst of the fall and winter surge that had long been predicted and feared. More than 18 million Americans have been diagnosed with coronavirus in 2020 and more than 321,000 have died. But soon the darkest days will be over.

The vaccines work. Their rollout may not be perfect and there may be setbacks, but Fauci's tone, while sober as ever, carries a hopeful note. "It's not all despair," he said recently in one of his innumerable television interviews.

He and Grady will spend their free time in the coming months walking together by the river, not merely exercising but also watching the change of the seasons, looking for birds, enjoying the healing power of nature.

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"Clearly what drives him is his work, his mission, his feeling that he's got really important things to do and he can contribute to them," Grady said. "But I think what's interesting about Tony that people may not know is that the things that make him happy are pretty simple things."

She said her husband has become delighted with a houseplant. It’s a hibiscus. He didn’t think it would make it through last winter, but it survived, and they’re optimistic it can make it through this winter as well.