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People who know Maria Van Kerkhove describe her as someone who has worked her whole life to be in this place, at this moment.

This place is at the core of the World Health Organization’s coronavirus team, this moment is when the WHO is trying to steer the globe’s response to the Covid-19 pandemic. No one would expect such a job to be anything less than highly stressful, but lately, the ride has been a rocky one.


Van Kerkhove, who for months has joined Director-General Tedros Adhanom Ghebreyesus during regular press briefings, found herself in a firestorm last month after saying that people with Covid-19 who are asymptomatic very rarely transmit the infection.

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The agency’s pandemic response team, which Van Kerkhove helps lead as the head of the WHO’s emerging diseases unit, came under fire again this week when more than 200 scientists accused the WHO in an open letter of resisting evidence that virus-laced aerosols — emitted by people infected with Covid-19 — are fueling spread of the disease.

While the latter critique was aimed broadly at the WHO, Van Kerkhove was personally in the hot seat in the case of the earlier controversy. At the time, she was speaking about people who never develop symptoms. But “asymptomatic” is also a term sometimes used to describe people who are infected and who haven’t yet developed symptoms. It’s been established those people can and do transmit the infection.


Covid-19 Twitter erupted after Van Kerkhove’s remarks. The following day, she and Mike Ryan, the head of the WHO’s health emergencies program, turned to Facebook Live to clarify the comments.

“She should have recognized that’s how it would get interpreted,” Ashish Jha, director of Harvard’s Global Health Institute, said a couple of days later. “Even the next day’s walk-back … I just don’t think they clarified it well enough.”

Van Kerkhove, who strives for precision in her Covid-19 messaging, is still bruised by the episode.

“I was talking with my husband [recently] and I was saying I’m struggling at the moment with the pushback and the second-guessing and the challenging,” she told STAT in an interview. “I’m trying to get information out to help people. I’m trying to get the information out to clarify WHO’s position, which is to help people, which is to suppress transmission and to save lives.”

“There’s no other motivation. So, the idea that, you know, we’re doing things that could potentially be harming people and hurting people, it’s very difficult for me to rectify,” Van Kerkhove said.

To that end, Van Kerkhove and others at the WHO have written hundreds of guidance documents on Covid-19 — on breastfeeding while infected (encouraged when possible), on preparing hospitals for surges in patients, on controlling spread of the virus at border crossings, to name but a few.

Ryan described the incident as “a storm in a teacup.” When Van Kerkhove wanted to clarify her statement the following day, he joined her online. “Through that whole thing she showed just immense courage and character,” he said.

Ryan, of course, is hardly unbiased. “Certain professionals, you almost feel like they’ve spent a lifetime preparing for a role — a role they didn’t know they were going to have,” he said in a recent interview. “She feels like someone like that to me. Someone who’s been subconsciously preparing for the big one.”

Indeed, Van Kerkhove’s awe of science germinated early on. Her twin sister, Alisa DeJoseph, with whom she grew up in upstate New York, recalls being “the right brain,” excelling in the arts, while Maria was “the left brain,” excelling in math and science.

Peter Goodfriend, who taught Van Kerkhove advanced placement biology her senior year of high school, said he once videotaped and brought into class a TV segment about “The Hot Zone,” Richard Preston’s just-released bestseller on Ebola. He also bought and read the book, then lent it to Van Kerkhove — “one of those students who just stand out,” as he put it.

It made an impression. Van Kerkhove, now 43, said she remembers trying to figure out the careers of the characters Preston wrote about. Some were virologists, she knew. But there was another set of professionals, doing a job she hadn’t previously heard of: epidemiologists.

“I thought the idea of understanding why certain people get sick, why others don’t, what were those differences? That was quite fascinating. Almost detective-like,” she said.

Pursuit of this newfound career path took Van Kerkhove to some of the best universities around. They were also places where degrees don’t come cheap — Cornell, Stanford, and the London School of Hygiene and Tropical Medicine, where she got a bachelor of biological sciences, a master’s in epidemiology, and a Ph.D. in infectious disease epidemiology, respectively. “I had a lot of student loans,” she said.

During summer breaks at Cornell, she did field work on projects run by her professors — traveling to Mexico, Venezuela, and Costa Rica. Sometimes the research involved studying the plants indigenous peoples used for medicinal purposes; one summer she was studying leaves and fruits capuchin monkeys rub on their fur. Decades later she recalls how dark the nights were, the constant chorus of frogs, the tang of freshly squeezed juice in the mornings.

After Cornell, Van Kerkhove was accepted to Stanford to do a master’s degree in epidemiology, a one- or two-year program that she completed in one. She then pressed pause on her studies, moving to New York City to take a job as an epidemiologist for Exponent Health Services Practice, a consulting firm. Much of her time was spent on the issue of power line expansions and the fears of communities that electromagnetic fields emitted by them could cause cancers.

In what people who know her well would probably describe as classic Van Kerkhove behavior, she dug in, trying to learn everything she could about the subject. The experience taught her how to weigh evidence, she said, and the critical importance of risk communications — one of the skills she’s leaning heavily into in the Covid-19 pandemic.

“What I tried to do was link the science to the concern and tried to explain, you know, what I could and alleviate some fears,” she said.

With some of her student loans paid off, Van Kerkhove was ready to pursue a Ph.D. She wanted to study at an institution that focused on global health. Enter the London School of Hygiene and Tropical Medicine.

This was the mid-2000s, when bird flu — the H5N1 virus — was racing through Asia and beyond, decimating poultry flocks. It rarely infected people, but when it did, the outcome was more often than not fatal. About 60% of people known to have been infected with that virus died.

Van Kerkhove spent the better part of two years shuttling between London and Cambodia, where she worked with scientists at the Pasteur Institute in Phnom Penh, trying to chart the movement of poultry in a country where commercial-scale poultry production didn’t exist.

In Cambodia, Van Kerkhove charted the movement of poultry as bird flu was racing through Asia. Courtesy Maria Van Kerkhove

The study Van Kerkhove and her Cambodian colleagues produced showed that infected poultry entering the country from China made its way through Vietnam to Cambodia through a series of middlemen. It became the subject of Van Kerkhove’s Ph.D. thesis. “That was a great piece of work,” said Malik Peiris, a world-renowned virologist at Hong Kong University who was one of the thesis reviewers and was later a colleague on Van Kerkhove’s work on MERS, a camel coronavirus.

A number of the Cambodian scientists Van Kerkhove collaborated with remain at the Pasteur Institute. Sowath Ly, who is now deputy head of the institute, said they marvel to see the scientist with whom they quizzed Cambodian villagers about bird flu sitting beside the director general of the WHO informing the world about Covid-19.

“We are very proud of her,” said Ly, who described Van Kerkhove as a good mentor.

Others are more reserved about the WHO’s handling of the pandemic response. Jha, the Harvard expert, described the agency’s communications efforts as “good but not great.” (Still, he credited the agency for communicating at all, noting that the Centers for Disease Control and Prevention barely briefs at all these days.)

Multiple people who have worked with Van Kerkhove talk about her “laser focus” and her prodigious capacity for work.

While doing postdoctoral work at London’s Imperial College under prominent mathematical modeler Neil Ferguson, she became a liaison between Ferguson’s group and the WHO’s influenza team. Effectively, Ferguson lent Van Kerkhove to WHO; for a number of years she traveled weekly from London to Geneva to lend a badly needed hand.

She worked under Tony Mounts, a CDC infectious diseases epidemiologist who was at the time seconded to the WHO. Van Kerkhove’s productivity intimidated some of his other staff, Mounts recalled, “because she was so efficient that she tended to run circles around people at times.”

When the 2009 influenza pandemic began, his unit tapped into that capacity, producing with her help important papers assessing the risk factors for severe H1N1 infection — that is the flu strain that triggered the pandemic — and estimating global mortality.

“It’s really stuff we couldn’t have gotten done without her. We just didn’t have the time or the people or the expertise on our team without her to do that,” says Mounts, who is now on assignment to USAID. “She just kind of buckles down and gets work done.”

In 2015 she was hired by the Institut Pasteur in Paris to create a network of rapid outbreak response teams throughout the famed organization’s 33 branches worldwide. Van Kerkhove speaks well of the experience, but friends say she didn’t get the support she needed to make the goal a reality. Two years later the WHO was looking for someone to head its coronavirus work. It was a job she wanted, and back to Geneva she went.

Around Christmastime last year, Van Kerkhove was in North Carolina with her husband, Neil, and their two children. They were visiting family when she got a phone call that changed the tenor of the vacation. A mysterious virus spreading in China, she was told. A couple of days later, she was en route to Geneva again.

The work has been nonstop since.

Van Kerkhove was part of the WHO’s nine-day mission to China in February to study the new disease and China’s response to it. After her return to Geneva, some staff at WHO headquarters contracted Covid-19. Fearful she’d bring the virus home to her family, Van Kerkhove decided to quarantine herself when she was at home.

For at least two months, she didn’t touch her children: Cole, now 9 ½, and Miro, who is 18 months old.

She often left for work before they were up, arriving home after they were in bed. When she was home, she sequestered herself in a room — a technique many frontline health workers have used in this pandemic. She would talk to her children through windows. “It was awful. Awful!” she shuddered.

Maria and Miro
Van Kerkhove, fearful she may have been infected with Covid-19, communicated with son Miro only through the windows of their Geneva home for at least two months. Courtesy Maria Van Kerkhove

Cole, who had initially been excited his mother was trying to help the world respond to a crisis, became convinced she’d die from the new disease when she went to China. Miro thought his mother was playing a game of hide and seek, and would run after her whenever he saw her.

“I would laugh in front of him and then come into the bedroom and cry because it was just a horrible, horrible thing,” she said. Eventually the rate of new infections in Geneva started dropping, schools reopened, and there were no recent cases among WHO staff.

“There was one day that I came home and … I was on front lawn, and the baby just ran up to me and I just grabbed him. I just couldn’t do it anymore,” Van Kerkhove said.

She credits her husband for being “incredibly supportive,” but acknowledges 2020 has been a slog.

“It’s difficult for all of us. I haven’t been home a lot in six months,” she said.

  • In any uncertain situation like this one, no matter the field, the people working in it have to begin with limited information, and will sometimes make the wrong choice or misinterpret incomplete information – because the circumstances demand it. All anyone can do is move on and try again.

    With a virus that has never been experienced, it must be terrifying to take on the task of trying to figure out how it works, what it does, how best to deal with it, knowing that lives may well depend on getting something right as quickly as possible. I admire Dr. Van Kerkhove for being willing to do the really hard job of navigating that minefield – and put her own life at risk. Criticism is inevitable, as everyone feels the pressure of trying to get as much information as quickly as possible, in the face of a rapidly spreading and often deadly disease. Media is often foolish in how they tell the story. I do not think that helps anyone.

    I am not in the medical field, but I am a retired environmental scientist who also dealt with human health issues. I share that same kind of passion about what I did, and would still be doing it if I could, so I get it. I am right now still at the tail end of recovering from Covid-19, one of those lucky “vulnerable elders” who made it through early on, without having to be hospitalized (though not without some scary moments).

    I am deeply grateful for Dr. Van Kerkhove and the many other epidemiologists, clinicians and others whose drive and dedication provided so much information as quickly as they did. It didn’t matter that the information seemed to be changing almost on a daily basis. I felt reassured by that. It meant that people were sharing information and testing it out. And ultimately it helped those who diagnosed me with Covid-19 despite a false negative test and helped me make good decisions. I have no way to thank the many people, from lab to field to care centers, who are responsible for my being alive and relatively healthy, including Dr. Van Kerkhove.

    And I have to add that I am proud that my youngest daughter is currently a graduate student in Public Health and Epidemiology.

  • Most of us unconsciously believe that brilliant, dedicated people will always make the correct decisions in critical situations. But of course that’s often not true. The more interesting story, by far, is how such a person copes with being wrong. It appears – I’m just a layperson trying to get answers – that Van Kerkove may have been part of two tragic WHO blunders: tardy recognition that the virus could be transmitted by asymptomatic persons; and tardy recognition of the danger of indoor aerosols. Branswell avoids those subjects. To experience journalists trying to confront these difficult issues, listen to today’s “The Daily” podcast by the New York Times.

  • Thanks for an excellent article Helen, charting the career path of a dedicated and courageous Public Health professional. Quite inspiring really, especially as she is the only woman we see at the WHO head table in the news these days.

  • I marvel at what Maria has accomplished and what she is doing now. She is a human being of the highest caliber and integrity. Thank you Maria for your tireless work and immense level of commitment.

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