President Biden's chief medical adviser, Dr. Anthony Fauci, tells "Axios on HBO" that despite the effectiveness of the COVID-19 vaccines, emerging variants could pose a "stumbling block" and Americans shouldn't become complacent.

Driving the news: The director of the National Institute of Allergy and Infectious Diseases also shared his thoughts on contemplating his own mortality, working with Biden, and talking to teachers about returning to school before everyone's been vaccinated.

Fauci called the suffering and death of recent months "stunning," with January and December the worst months since the start. "The number of cases were between 300,000 and 400,000 per day," he said. "The number of deaths were between 3,000 and 4,000 per day."

• While "things are going in the right direction ... we're also going to be challenged by the appearance of variants or mutants that have appeared, some of which have a functional influence on how we're gonna respond to them," he said. "Fortunately, others are well covered by the vaccine, but not all of them."
• "You don't want people to become complacent. We still have a long way to go ... We still might have a stumbling block coming with the appearance of variants that would dominate the picture."

The other side: Fauci, who has been vaccinated, expressed optimism that as more Americans receive their doses, friends or relatives who have both been vaccinated can finally reunite as they'd like.

• "Can I have my daughter come down from Boston, who I haven't seen in a very long time?" he said. "Can I sit down and have a dinner with her without worrying about spreading infection? Can I give her a big hug the way I'd like to? I think the answer ultimately will likely be yes to that, but I think we'll wait to see what the recommendations show."

In talking with teachers, Fauci said, "You have to understand and empathize with them greatly, that they have a concern of their own safety, so you can't downplay that."

• "You also have to fight for resources to be able to allow the schools to open up safely. So the provision of masks, of good ventilation, of good spacing of seats, all of those things together are going to get the schools open safely."
• He said of his task in offering guidance to all Americans, "It's sometimes humbling because you have to make a decision based on incomplete data."

Fauci, 80, said he faced his fears that the virus could get him, especially during Donald Trump's presidency.

• "I didn't fixate on that, but it was in the back of my mind because I had to be out there," he said. "I mean, particularly when I was going to the White House every day when the White House was sort of a super-spreader location."
• He said he's committed to telling any president hard truths, but doesn't stress about that much now because Biden is "very wedded to the concept of 'science rules' and you act on basis of what the data and the scientific evidence tells you to do."

The bottom line: Fauci said he's aware that to some he's a cultural icon, while others have made threats against him and his family — but he tries to block both out and stay focused on the pandemic. "Right now, my responsibility is from a scientific standpoint to do whatever I can to end this."