For those who weren’t tuning in to the daily White House coronavirus press briefings earlier in the coronavirus outbreak — and who may now be actively tuning pandemic updates out — the woman whom both President Trump and House Speaker Nancy Pelosi turned on over the weekend may be an unfamiliar face.

In fact, Dr. Deborah L. Birx, 64, is a world-renowned global health official and a retired U.S. Army physician who was instrumental in HIV/AIDS vaccine research, and whose career has spanned three decades. And ever since Vice President Mike Pence appointed her as the response coordinator for the White House Coronavirus Task Force — one of two women on the team — she’s been on national TV almost daily, often alongside Dr. Anthony Fauci, the nation’s top infectious-disease expert.

But on Sunday morning, Pelosi questioned Birx’s credibility on ABC News’ “This Week,” where she criticized the doctor for not doing more to refute the president’s inaccurate remarks about the coronavirus. “I think the president is spreading disinformation about the virus and she is his appointee,” Pelosi said. “So I don’t have confidence there, no.”

Read more: Coronavirus tally: Global cases of COVID-19 top 18 million, 689,625 deaths, Dr. Birx says US in ‘dangerous new phase’

Later Sunday, Birx struck a more dire tone on CNN’s “State of the Union,” where she said that we are in a “new phase” of the pandemic, and warned Americans in rural areas that “you are not immune or protected from the virus.”

And this has led to mixed messages from the White House. While communications director Alyssa Farah tweeted Sunday that Pelosi was “deeply irresponsible” for repeatedly trying to “undermine & create public distrust in Dr Birx, the top public health professional on the coronavirus task force,” the president called Birx’s response to Pelosi’s criticism “pathetic” on Twitter TWTR, +7.09% Monday morning.

Related: Trump blasts Dr. Birx as having taken Pelosi ‘bait’

Birx has been a scene stealer before — such as when she warned younger Americans that they were not immune to COVID-19, stating, “millennials are the key” to stopping the spread of the virus.

But her body language as President Trump suggested bright-light treatments and disinfectants to fight the coronavirus in April — sitting still, taking a deep breath, blinking, setting her face still and then staring at the ground — really blew up on social media this spring. Even then, some criticized her for not standing up and refuting the president’s comments immediately.

Read more:Trump suggests disinfectant as treatment for coronavirus ‘by injection inside or almost a cleaning’ — later says he was speaking ‘sarcastically’

Others set the clip to the theme music from HBO’s “Curb Your Enthusiasm,” or joked about her facial expression. “You can see Dr. Birx’s soul leave her body,” snarked one tweet.

(The president later responded that he was asking the questions “sarcastically,” and the White House press office accused the media of taking his comments “out of context.”)

Related: Chris Cuomo satirizes Trump’s disinfectant-injection suggestion: ‘Take two shots of Windex, swallow this lightbulb, and call me in the morning’

For those curious to learn more about Birx, however, here are five things to know about the ambassador-at-large’s 30-year career, and her current role as the federal coronavirus response coordinator.

She was always a science buff

Birx grew up in Pennsylvania, where she and her two older brothers converted the backyard shed into a makeshift lab. Their most notable invention: a satellite-dish antenna that they moved around on roller skates, the Society for Science & the Public reported. When Birx was a junior at Carlisle High School in Pennsylvania, she competed in the 1973 International Science and Engineering Fair in San Diego. Her project on paleobotany in the Carboniferous period scored the trophy for girls grand champion, plus a chance to compete in the Army and Navy’s International Science and Engineering Fair (which she won). She eventually put herself through medical school at the Hershey School of Medicine at Penn State, the Hill reported.

She has a military background

Birx trained in internal medicine and clinical immunology at the Walter Reed Army Medical Center and the National Institutes of Health, according to her biography on the Department of State website. She began her government career as a military-trained clinician in immunology, mainly researching HIV/AIDS vaccines, in 1985. She attained the rank of colonel, and as Col. Birx received two prestigious U.S. Meritorious Service Medals and the Legion of Merit Award. She was named the director of the U.S. Military HIV Research Program at the Walter Reed Army Institute of Research, serving from 1996 to 2005. And she led “one of the most influential HIV vaccine trials in history,” her bio states.

Related:Dr. Fauci tells MarketWatch: I would not get on a plane or eat inside a restaurant

She’s worked closely with three U.S. presidents — and was dogged in getting George W. Bush’s attention

When Bush announced his President’s Emergency Plan for AIDS Relief (PEPFAR) in 2003, Birx flew back from Kenya and waited outside of the then-director of the Office of National AIDS Policy’s town house for almost a week to get a meeting with him. She had been working on HIV vaccine research in Africa for almost six years at that point. So she showed him a 180-slide PowerPoint presentation “until he agreed ... to let the Army also be part of PEPFAR,” she told a George W. Bush Presidential Center podcast in September. “I was not leaving his office, and so I wore him down.”

Birx was later appointed ambassador-at-large and global AIDS coordinator by President Barack Obama, and she has overseen PEPFAR at the State Department for the past six years. Now she is also aiding the government response to the coronavirus under the Trump administration. Vice President Pence has described her as his “right arm” in that role.

Her signature scarves have built a following

As Birx tends to wear patterned silk scarves during press conferences and interviews, viewers have taken note, and even fashion cues, the Wall Street Journal reported. Instagram FB, +2.66% accounts dedicated to her neckwear have sprung up, including @deborahbirxscarves and @deborahbirxscarfqueen. Some followers have posted pictures of themselves sporting similar scarves to hers on Twitter:

Why was Birx sporting scarves even before people started using them as makeshift face masks during the pandemic? Turns out, it’s one of her tips for packing lightly and sticking to just one carry-on bag when traveling for work. “I take relatively plain dresses, black and other colors, that you can then change the scarves on, and through that it looks like it’s a totally different outfit,” she told the Strategerist podcast last year.

She throws one heck of a Christmas party

Birx takes a hands-on approach to all of her work, including her annual Christmas Eve party. The Washington Post revealed in a lengthy profile that she hosts a 24-hour buffet for almost 100 people in her home on Christmas Eve every year, and that she and a deputy cook all of the food themselves. “It’s important that I do this myself,” she said. “We do this to show love.”

The Post profile also notes that she graduated from high school at 16, got married and graduated from college at 20, finished medical school at 23 and had her daughters shortly after — so she’s juggled work and home responsibilities through her entire career. On weekends in the 1980s, “Birx’s older daughter would sit on the floor of the lab, playing with the colored caps of sample tubes, while Birx cultured HIV.”

Stay up-to-date with MarketWatch’s coronavirus coverage here.

This article was first published in April 2020, and has been updated with recent comments Trump and Pelosi have made about Birx.