It was a key encounter with a mentor during her residency at the University of Colorado that helped put epidemiologist Mary Hamel, MD, DTM&H, on the path to becoming a world leader in the fight against malaria.
First, though, came a broader desire to help people in Africa who were suffering.
“When I was young, I saw on TV the devastation of famine and illness in Africa,” Hamel says. “I was drawn to helping. The intellectual part came later. First, I would say, it was an emotional response that drew me to medicine.”
After graduating from Occidental College in Los Angeles with a bachelor’s degree in biology, Hamel went to Sudan in northeast Africa on a four-month volunteer project with Operation Crossroads Africa. “I saw the effects of poverty and illness in a resource-poor country,” she says, “and I also saw the beauty of the community and the traditions there, and it really appealed to me.”
Hamel earned her MD at the University of Vermont in 1992, then came to what was then the CU Health Sciences Center for her internal medicine residency, with Africa still on her mind.
“It was at the end of my residency at CU, and I wanted to be a doctor in Africa,” Hamel says. “I called Doctors Without Borders from the nursing station at the hospital and I found out that the pay was less than my student loan payment. Then I called the United Nations High Commissioner for Refugees agency and that pay was just above my student loan repayment amount. So my dream seemed to be unattainable.”
After those calls, Hamel’s attending physician walked by – Steven Mostow, MD, at the time a nationally known infectious-disease specialist and associate dean at CU. (Mostow died when the small plane he was piloting crashed in 2002.)
“He noticed that I was looking distraught, I guess, because he asked me what was wrong. When I told him what had happened, he said, ‘You’ve got to go to the CDC and do the Epidemic Intelligence Service fellowship.” It’s a globally recognized post-doc epidemiology training program for what the CDC calls “disease detectives,” with a focus on field work.
Left: Mary Hamel, MD, DTM&H, looking through vaccination registers at a clinic in Malawi. Center: Hamel with a child in Kenya during one of the vaccination studies on which she was a principal investigator. Right: Hamel at at Siaya District Hospital in western Kenya, where she conducted many of her malaria studies. Photos provided by Mary Hamel.
That set Hamel on the course to becoming a top researcher on malaria and a leader of international efforts to combat the disease over the last three decades, with time out in the late 1990s for a two-year fellowship at the CU Division of Infectious Diseases, which included a rotation at the Universidad Peruana Cayetano Heredia, in Peru, to study tropical medicine.
Hamel spent 23 years at the U.S. Centers for Disease Control and Prevention, where she rose to become chief of the research unit in its Malaria Branch. While with the CDC, she became senior technical advisor to the U.S. President’s Malaria Initiative. And for six years she lived and worked in Kenya at a joint Kenya-U.S. research station, directing its malaria program. While there, she would occasionally call another CU mentor – Nancy Madinger, MD, an infectious-disease professor – for advice on a puzzling case.
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In 2017, Hamel moved to the World Health Organization, based in Geneva, Switzerland, where she now lives. Hamel has led WHO teams supporting implementation of malaria vaccine initiatives while facilitating the development of next-generation vaccines.
The WHO program she has led for several years supported pilot use of the world’s first malaria vaccine, RTS,S/AS01, and she led the WHO review of a second malaria vaccine, R21/Matrix-M. Last year, she and her team were awarded the WHO Director-General’s Award for Excellence for scientific leadership and coordination of the vaccine pilot implementations.
In addition to working on vaccines, Hamel has led numerous malaria-related studies, primarily in Africa, focusing on malaria in children, pregnant women, and people living with HIV, as well as transmission reduction efforts. And she continues to do work in Africa frequently.
Left: Mary Hamel, MD, DTM&H, and her colleagues donating blood for use in hospitals at their research center in Africa. "Severe malaria in children in these areas often manifests as severe malaria anemia, and blood transfusions are lifesaving," she says. Center: Hamel and Jérôme Salomon, an assistant director-general of the WHO, in Cameroon, in a central cold room with the nation's first delivery of malaria vaccine behind them. "It was a very emotional moment," she says. Right: Hamel being interviewed during the first vaccine launch in Malawi. Photos provided by Mary Hamel.
Malaria – a life-threatening disease caused by a parasite carried by mosquitoes – is one of the world’s most severe public health problems. According to WHO, there were an estimated 249 million malaria cases in 2022 and 608,000 deaths across 85 countries. The vast majority of cases are reported in sub-Saharan Africa, but the disease can be found in other tropical and sub-tropical areas of the world.
Children under 5 account for about 80% of all malaria deaths in Africa. Pregnant women, travelers, and people with HIV or AIDS also are at higher-than-average risk of severe infection.
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“Malaria is devastating,” Hamel says. “In malaria-endemic areas of Africa, every family has lost a loved one – a child, a brother, a sister, a cousin – to malaria. And yet it’s preventable and treatable.”
In areas at risk, Malaria can be prevented by keeping mosquitoes away through such means as sleeping under mosquito nets or by taking intermittent treatment doses of antimalaria drugs. All preventive measures, including malaria vaccines, can reduce, but not completely prevent, malaria. There are various medicines for infected people depending on the type of malaria, but the most severe type of malaria, P. falciparum, can progress rapidly from fever to death – often too rapidly for the sick person to reach care.
“I moved full time into malaria because there was so much potential for progress,” Hamel says. “It’s an area where you could see making an impact.”
Before 2000, about 1 million children died of malaria each year, she says. “In 2000, we had a renewed commitment to malaria from heads of state and policy makers, the President’s Malaria Initiative began, and The Global Fund to prevent HIV, TB, and malaria was established, so there was more funding going towards malaria. We were able to get reliable drugs into countries and scale up distribution of bed nets, and we’ve seen malaria deaths drop by half.”
But the steady decrease in deaths stalled around 2015. “We came to the point where we weren’t making gains with the tools we had, partly because there were barriers to scaling them up, and partly because none of them is 100% effective,” Hamel says. “And so scientists continue to search for more effective interventions that can be brought to scale. In recent years I’ve been working on malaria vaccine studies, among other interventions.”
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After a clinical trial for which she was a principal investigator showed efficacy for RTS,S/AS01, the first-ever vaccine to immunize against a human parasitic infection, “I was asked to come to WHO in 2017 to lead the effort to introduce it in Africa through a pilot program and also do a rigorous evaluation of the impact, safety, and feasibility of delivering it widely,” Hamel says.
In the four-year pilot program, more than 2 million children received RTS,S/AS01 – known as Mosquirix – through their routine immunization clinic visits. WHO recommended wider use of the vaccine in 2021, followed by approval of a second vaccine, R21/Matrix-M, in 2023.
With these vaccines now available and scaling up across Africa, Hamel expects that “we’ll see the trend in malaria deaths go down again.”
Left: Mary Hamel, MD, DTM&H, and members of her WHO team in Geneva, who she describes as "so dedicated to bringing the malaria vaccine to children at risk." Right: Hamel's team receiving the WHO Director General Award for Excellence, 2023. Photos provided by Mary Hamel.
Other obstacles to fighting malaria in Africa remain, such as the fact that sick children and their families in remote areas may have to walk through the dark to a tiny clinic for treatment, and then find the lone clinician has gone home for the night. “There are a lot of barriers to getting treatment early enough, which makes prevention that much more important,” Hamel says.
There’s a fair amount of diplomacy to Hamel’s work for WHO. In her vaccine rollouts and other projects, she has represented the agency at high-level meetings and met with national ministers of health and finance, public health agencies, funders, and the media. There are differences to be worked out and understandings to be reached.
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In that role, Hamel says she draws on her CU residency and fellowship training.
“We often spoke to patients or families about something very serious, and you had to think about how to approach things in a professional but caring way,” she says. “And that prepares you well for the kind of work I’m doing now. You have to listen carefully, stay focused, and think about the important points that need to be made. You also have to hold back your preconceived notions, listen to all these other viewpoints, and incorporate that into the final product.”
On Oct. 4, Hamel returned to CU Anschutz to present a Pediatric Grand Rounds lecture on her work on introducing malaria vaccines. She also met with Division of Infectious Diseases leaders.
Hamel looks back at her time at CU, and the connections she made there, with fondness. She notes that one of her “fellow fellows” at CU, Michelle Barron, MD, is at CU Anschutz Medical Campus today as an infectious disease professor. And several of her health colleagues in Geneva – including some at The Global Fund – have CU connections.
“Those were such formative years for me, the mentorship there was wonderful, and the doctors and nurses there were so caring and compassionate,” she says. “I’m so fortunate to have been at Colorado.”
Photo at top: Mary Hamel, MD, DTM&H, at an outreach vaccination clinic in Malawi. Photo provided by Mary Hamel.