Of the three people leading the US response to coronavirus only one, Dr Deborah Birx, has previously been on the frontline against a mysterious virus which scientists couldn’t stop.

It was the 1980s and Birx was fresh out of medical school. The virus was HIV.

At the medical center where Birx worked as a US army physician, healthy young men were dying in droves from an illness no one could name.

“When you’re trained in medicine and it’s the 80s and you’ve got all this hi-tech stuff and this ability to diagnose everything,” Birx said in a Sep 2019 interview with the George W Bush Presidential Center, “when you not only couldn’t make a diagnosis, you didn’t know what the problem was, and you didn’t know how to treat it, it was devastating.”

But instead of being cowed, Birx twisted her heartbreak and confusion into research and treatment. In doing so, she embarked on a career dedicated to stopping HIV and Aids.

Having gone head-to-head with global health leaders while overseeing a program responsible for saving millions of lives, Birx has become something of a legend in the global health community.

Now her task is to stop the spread of Covid-19.

“When it is a matter of making tough decisions, she will do it,” said Dr Carlos del Rio, a professor in the global health department at Emory University who has known Birx for more than 20 years. “And that, to me, is what we need right now.”

Birx will also need to manage her role in a tumultuous White House, where she has been placed as one of three people leading the US coronavirus response.

The vice-president, Mike Pence, is overseeing a taskforce led by the health secretary, Alex Azar, but has said Birx is his “right arm”. It is an unusual arrangement but Birx, one of the few political appointees of Barack Obama to survive into the Trump years, has made clear she can operate in such an environment.

In 2014, Obama appointed her ambassador-at-large and global Aids coordinator. The latter role gave her control of the the largest effort by any country to stop a single disease, the President’s Emergency Plan for Aids Relief, or Pepfar. According to the state department, more than 17 million lives have been saved.

At Birx’s swearing-in, the secretary of state, John Kerry, shared how her foresight and intelligence about the disease may have saved her own life in 1983, when Aids was still a mystery.

Birx was giving birth to her first daughter and had lost a significant amount of blood, Kerry said. The doctor ordered a transfusion but Birx had read a report about the mystery disease and the risks of such a process.

“Do not let them give me blood,” she screamed, before passing out from pain.

Her husband followed her orders, stopping a transfusion the hospital later revealed would have been contaminated with HIV.

“It made her think hard not just about the perils of this new disease, but about her responsibility to fight it,” Kerry said.

In a September 2019 interview, Birx explained how the sacrifices of infected soldiers helped define her commitment to fighting the disease.

“They died with such courage and such willingness to try different things, realizing it may not help them, but it would help the person behind them,” she said. “I just never saw that level of altruism, amidst just death and despair, from the patients themselves.”

She spent the next two decades helping to lead an influential HIV vaccine trial and providing important contributions to understanding the disease in the military, where she was promoted to colonel. She was lured out of the military after George W Bush started Pepfar in 2003.

The program began when drugs to manage HIV/Aids and prevent its transmission were available in the US but not in Africa, where millions were dying. Birx joined two years later, overseeing programs led by the Centers for Disease Control and Prevention (CDC).

Her work has taken her around the globe to study and learn and to ensure US money funding such programs is used effectively. Del Rio, who chairs the scientific advisory board for Pepfar, said Birx had confronted global health leaders misusing US funds.

“She doesn’t say, ‘We’ll give you another opportunity,’” he said. “She stands up to a minister of health and says: ‘I’m sorry but we’re not doing that.’”

At one point, the World Health Organization called for people to stop using a HIV/Aids medicine. Scientists at Pepfar thought it was the wrong call. Birx listened to them, then ignored the WHO.

“At the end of the day, she was right,” Del Rio said. “This is the right decision. She listened to the data, she looked at the data and she said, ‘Let’s proceed.’ She is a bold leader. I have a lot of respect for her.”