2025-26 PopTalks Series

Global health finds itself at a crossroads. Extraordinary challenges persist, but disruption also creates opportunities to reimagine the system. How are we going to build it better?

That was the crux of the PopTalks discussion on September 23, 2025, when two department chairs at prominent public health institutions sat down - our own Dr. Thoai Ngo with Dr. Judd Walson, Chair of the Department of International Health at Johns Hopkins Bloomberg School of Public Health.

Their conversation came at a critical time. Earlier this year, the United States government made a policy choice to step back from its role as a global health leader, dissolving USAID as an independent agency. Roughly 90% of the agency’s programs were terminated, leaving life-saving initiatives around the world in limbo and tens of millions of people at risk.

Meanwhile, on September 18, 2025, the U.S. Department of State released its America First Global Health Strategy. It took the focus away from the bread-and-butter public health work that has improved survival and quality of life worldwide.

“While the strategy emphasized some principles that are quite important––integrated-programs, efficiency, and investment in frontline workers––it deprioritized some critical areas, such as reproductive health, maternal child health, and vaccines,” Dr. Ngo explained.

The funding pullback threatens decades of progress. The U.S. had provided about 42% of all donor government assistance. So far, no other nation has yet to step up to fill the gap.

Looking Back to See Forward

“None of us has magic answers,” said Dr. Walson. “History is an amazing teacher. How did we get here?”

In 1960, maternal mortality, child mortality, and infant mortality were all much higher, while women’s literacy was low. “There was no structure or funding landscape for public health,” explained Dr. Walson. “No Gates Foundation, no USAID. And yet, a small group of dedicated people rolled up their sleeves and started to make a difference. Yes, we’ve hit a stumbling block. But if we come together to meet the challenges, I do think there is hope in this moment.”

Strong political motives spurred foreign assistance. “We, who do this work, lost sight of the political thread that drove the motivation,” explained Dr. Walson. “We assumed everyone should do this because it’s the right thing to do. But political decisions are made for a lot of other reasons - humanitarianism alone is insufficient.”

The America First Global Health Strategy does have some positive principles worth acknowledging:

• Recognizes past U.S. leadership and global health success
• Calls for reducing dependency on foreign aid and investing in frontline workers
• Emphasizes data, accountability, and integration
• Encourages private-sector engagement

“There are some good nuggets there,” Walson reflected, “but the entire agenda is defined by self-interest, nationalism, and privatization.”

Partnership and People First

To move forward and build a better system, stakeholders need to prioritize strong partnerships and solidarity. “There’s a need for people to be part of something bigger than themselves –– like-minded people who see the value in solidarity,” said Dr. Walson, quoting Margaret Mead: “Never doubt that a small group of thoughtful committed citizens can change the world. Indeed, it’s the only thing that ever has.”

The promising path, added Ngo, lies with investment in on-the-ground healthcare systems where need is greatest. “We have to shift the money from disease eradication to people, systems, and communities.”

The current process — metrics-obsessed, politically driven, top-down, and vulnerable to sudden policy change — repeats old mistakes. Ngo and Walson agreed we should follow the lead of countries like Ghana, Rwanda, and Vietnam, where decades of investment in access to education, robust health systems, and community support have translated into dramatic gains in survival, life expectancy, and overall population well-being.

Stay Up to Date with PopTalks

The full, spirited conversation touched on data use, the legacy of imperialism, progress and setbacks in 65 years of global health - and even a little bit of Miles Davis.

To keep up with big ideas and fresh thinking in global health, subscribe to our newsletter

Millions of people recently encountered ivermectin on the Joe Rogan Experience, when guest Mel Gibson declared that the drug cures Stage IV cancer — despite no proven clinical rolefor the drug in cancer treatment.

How did we get to these unsupported claims, when just ten years ago the drug earned its creators a Nobel Prize? Blame a toxic stew of junk science, social media amplification, a global pandemic, and the all-too-human desire for miracles.

Dr. Carlos Chaccour, lead author of exciting new work on ivermectin in malaria prevention, joined our own Dr. Patrick Kachur on October 8, 2025 for a PopTalks discussion exploring the science and pseudoscience surrounding ivermectin. They examined the past, present, and future of this fascinating drug: how we got here, and how we can break free of myth and misinformation.

Ivermectin’s Early Years: Science Tackles Skepticism  

Ivermectin has transformed lives worldwideby treating parasitic infections like river blindness. Now, thanks to work by Chaccour and others, we find that it holds tremendous potential for malaria control.

But it faced skepticism from the very beginning. When studies of this veterinary drug in humans in the 1970s showed it had potential to eliminate parasite-driven river blindness, “there was massive distrust by academics, saying this will never work, no need for excitement,” Chaccour said. “Thank God they were wrong.”

The effort not only proved successful, it laid the groundwork for cross-national public health coalitions, and programs to control River Blindness successfully provided ivermectin (also known as Mectizan) to whole communities. “Today, this unprecedented drug donation is helping to eliminate transmission of the disease — an unfathomable concept when Merck first donated Mectizan,” according to the company’s Mectizan Donation Program.

Ivermectin Now: Misinformation Fills a Vacuum

Clinical trial after clinical trial paved the way for Ivermectin’s acceptance and adoption. Today, however, a general-purpose Google search for “Merck Ivermectin clinical trials” yields results led by articles on COVID-19.

“The medical community wasn’t on the same page during the pandemic,” Kachur noted as he and Chaccour broke down some of the lowlights:

• The White House’s promotion of two anti-malarial drugsto treat COVID-19, laying the groundwork for drug acceptance “based on ideology, not data,” said Chaccour
• Research reportsthat didn’t match realities on the ground
• Studies published by leading medical journals that were later retracted due to data integrity issues

Traditional means of challenging misinformation — like writing a letter to an academic journal — weren’t fast enough to keep up. “That created more confusion,” Chaccour said, “with the public thinking, ‘They don’t even agree—how can we trust them?’”

Doubts and discrepancies couldn’t stop flawed research from inflicting real-world repercussions. In the crisis of a global pandemic, countries were eager for treatments they could deploy right away, and some nations, including Peru and Bolivia, made ivermectin part of their national COVID policies.

Meanwhile, familiarity with ivermectin for veterinary medicine, coupled with misinformation on social media and limited access to healthcare, led to dangerous, off-label use in rural areas across the Western Hemisphere.

Not only did this endanger the people taking ivermectin, it “caused moral hazard,” Chaccour and Kachur emphasized. With ivermectin popping up in discussions of COVID treatments, people started to believe they didn’t need vaccines to stay safe. “Do Not Use Ivermectin Intended for Animals as Treatment for COVID-19 in Humans,” authorities like the State of Michiganwere forced to declare.

Today, even with widespread public debunking of false claims, and sound science backing ivermectin only for treating tropical diseases, misinformation about the drug persists. As states expand over-the-counter access, patients are requesting it for the wrong reasons. “No, the FDA did not 'quietly approve' ivermectin as COVID-19 treatment,” Duke Health bluntly declares. Even more dangerously, over the long term, an ivermectin cancer innovation fund in Florida is channeling $60 million of scarce research funding into unwarranted testing.

Getting Ivermectin Back on Track

We need ivermectin. But “how do we move on from the political?” asked Kachur.

• Engage with empathy and without judgement—“why do you think this?” rather than “please, you’re not a horse,” in Chaccour’s words.
• Be aware of the broader context “especially when dealing with unscrupulous adversaries. People are listening in and hearing that conversation and forming their own opinions,” said Kachur.
• Bring good detective work to emerging research and newly published studies. “If none make sense individually, then collectively they don’t make sense,” Chaccour noted.
• On a global level, decolonize public health messaging and action by “generating evidence and guidance and letting countries decide.”

Stay Up to Date with PopTalks

In the full conversation, Chaccour and Kachur lamented clinical trial research getting lost in a cyclone and joked about “their shared ancestry” and Kachur’s first impressions of Chaccour as a junior advisee.

“We were charged to help instill confidence in new candidates, and I thought, this is definitely one confident guy.” That confidence, he said, is sorely needed to navigate the setbacks facing global public health and champion the bold approaches required to move forward in areas like malaria treatment.  

To keep up with big ideas and fresh thinking in global health, subscribe to PopTalks updates.

The Rising Generation

The 2.2 billion young adults between 13 and 28—collectively, Gen Z—play a leading role in our planet’s story.

Equipped with unprecedented technology and the instincts of digital natives, this rising generation is facing down climate change, global conflict, misinformation, and corruption. They are tuned in, angry, and insisting that we find a better way.

How do you harness that riotous energy in service of civic life? The West African nation of Sierra Leone demonstrates the power of investing in opportunities for Gen Z, using the power of public policy to erase barriers and disadvantages—especially for women and girls.

Since 2018, 20% of the country’s discretionary spending has gone to education. Policies encouraging education and gender equity draw broad support across Sierra Leone, in sharp contrast with trends in many wealthy countries. One recent law requires 30% of political appointees to be women, for example. And leaders like Chernor Bah envision more to come.

Bah serves as Sierra Leone’s Minister of Information and Civic Education, a role to which he brings a passionate feminist perspective and a long history advocating for girls’ rights. On the heels of the 69th UN Commission on the Status of Women (CSW6), he joined Columbia’s Thoai Ngo for a PopTalks event where they discussed the challenges, opportunities, and urgent needs involved in empowering Gen Z as a force for good.

Education and Equality for Economic Growth

Sierra Leone is a young country—some 75% of the population is under 25 years old—and government investment is reshaping the lives of its residents.

Education is well-funded and strongly encouraged, and three out of four young people are now literate. The government invests heavily in STEM education, especially for girls; lunches are free, and school fees are banned by law.

And those investments, Bah said, have already paid off: as young people complete secondary education in record numbers, a massive wave of new students fills the nation’s universities.

“The nation’s investment in equality and youth are connected,” he said. “For us, investment in girls and women is the only chance for getting out of poverty.” When Ngo pushed for more policy details, Bah enthusiastically described some of what his government has done to protect women’s lives, careers, and contributions: they legislated against female genital mutilation for the first time in Sierra Leon’s history. They declared rape a national emergency and banned child marriage, and they’re fighting hard to decriminalize abortion.

Solving Problems at the Heart of a Climate Crisis

The Climate Vulnerability Monitor lists Sierra Leone among those nations most acutely affected by climate change. Together, Bah and Ngo recalled catastrophic mudslides devastating the capital city of Freetown in 2017, a deadly event that caught thousands by surprise. “The Global South is at the receiving end of the actions of the rest of the world,” Bah said. “That’s the reality this generation has to deal with.”

One example: extreme temperatures disrupt classroom learning. In South Sudan, similar heatwaves forced an adjustment to school calendars. “Too many kids were just fainting,” said Bah.

Sierra Leone has implemented innovative solutions, like heat-reflective roofing, to combat rising temperatures. With extreme heat just one of the many challenges facing the next generation, that spirit of innovation—backed by government investment—has proven valuable. Most schools still lack electricity, for instance, but students carry smartphones linked to a new nationwide 3G network and often powered by alternative energy sources, like solar chargers.

“We’re open and we’re progressing,” Bah said, “and we’re willing to take risks to try and see what works, with technology solutions that help solve real problems for real people who need it the most.”

The minister also pointed to the value of listening to communities. He cited the Sierra Leone tradition of planting a tree when a new child is born—a fortuitous tactic in the fight against deforestation. “It wasn’t climate action,” he explained. “It was something we did. It’s rooted into who we are.”

Gen Z Was Made for This

When Ngo asked, “What gives you hope?” Bah brought the conversation back to Gen Z—the “present and future” of his country.

“This generation is more connected and knows more about the world than any before it. They are constantly moving from one crisis to another. They are awake. They are aware of corruption and exclusion and governance failures—and they demand different things than the generation before.”

For Bah, those are positive traits, and they help explain why Gen Z is so central to his vision of Sierra Leone’s future. “We don’t think about this demographic as separate from our governing agenda,” he explained. “We ask ourselves: how do you invest in young people? They’re inundated with bad news because they’re so connected. How do you overcome such hopelessness?”

His government’s answer is to create a new sense of citizenship supported by four pillars: food security, public health awareness, digital citizenship, and climate action. Make a systematic bet in the lives, and abilities, of the rising generation. And, he said, harness and cultivate the sense that there might be “light at the end of the tunnel.”

Better Data, Bigger Questions 

Megatrends met migration patterns as we launched the all-new PopTalks conversation series, hosted by Columbia’s own Thoai Ngo and featuring Brian Thiede of the Population Research Institute (PRI) at Penn State. On February 17, 2025, nearly 130 in-person and virtual attendees gathered for a spirited discussion. The focus: Dr. Thiede’s recent work on the nuanced—and sometimes contradictory—health and demographic outcomes of climate shocks.  

“We face a rapidly changing world,” said Dr. Ngo in his opening remarks. “We need new frameworks and new thinking to confront climate crisis, aging societies, and the needs of the rising generation. Most of all we need new solutions, and that means changing how we do research on population health.”  

The PopTalks series aims to engage just those sorts of challenges, and this kickoff event wasted no time diving into the big questions.  

“Big Microdata” Captures Nuance and Exposes Research Gaps  

Our most reliable research methods have proven less than adequate for grappling with overlaps between climate, health, and migration. How do you nail down the effects of extreme weather events—droughts, wildfires, and heavy rainfall—on millions of people? Researchers like Dr. Thiede start by mapping out correlations in data on climate and health.  

His recent work with collaborators at PRI showcases both the value of “big microdata”—massive collections of individual-level data from surveys and censuses—and the need for interdisciplinary creativity to help us find solutions. His talk highlighted three recent examples.  

1. Who’s most at risk — migrants, or those who stay behind? 

The PRI team built a dataset tracking migration for some 55 million people in six Asian countries, all between 15 and 49—the prime age for migration. Then they modeled migration to other provinces as a function of unusual spikes in heat and rainfall. 

Previous research supports the idea that people tend to migrate away from drought-stricken areas, but Dr. Thiede’s team found the opposite: across all six countries, migration went down after sharp drops in rainfall. But when they zoomed in, the drop in migration was specific to China. In the Philippines, drought increased migration. In Indonesia, Malaysia, Nepal, and Vietnam, it had no effect.  

“These results complicate common narratives around displacement and ‘climate refugees,’” Dr. Thiede explained. “We usually frame this issue in terms of national security or anti-immigration policies, but what we see here is that and households adapt in ways that can be hard to predict, and vulnerability is distributed in complex patterns. Sometimes, the people most at risk are the ones who aren’t able to leave despite the danger of drought or floods.”  

2. Heat shocks and malnutrition: A hidden survivorship bias 

Using Demographic and Health Surveys (DHS) data from a 36-year period, Dr. Thiede and co-author Clark Gray dug into the connection between climate stress and nutrition. They modeled both short- and long-term malnutrition as a function of neighborhood-level exposure to heat and precipitation shocks.  

What they found surprised them: results were different for infants under two years old than for children aged three to five. The infants were less well nourished, on average, if their neighborhood or village had higher temperatures. For older children, the reverse was true.  

Untangling the mystery required a second set of models that uncovered a strong survivorship bias. Heat shocks correlated with higher mortality at all ages, meaning that only the healthiest children were reaching age three and showing up in the long-term data.  

“We need to be open to counterintuitive findings and pay close attention to possible biases,” said Dr. Thiede. “Population level health indicators are intertwined with mortality, migration, and fertility.”  

3. Complex causality in flooding and fertility 

Working with an interdisciplinary team, Dr. Thiede explored the effects of climate-related flooding on the fertility of women in Bangladesh. They found patterns that were clear, but complex. When more of the land around a village flooded during monsoon season, birth rates went up among women who already had two or more children, or had less than a primary school education. At the same time, fertility declined among women who had never given birth before and women who lived in cities.  

That kind of pattern was a key theme of the event. To understand how the stresses of climate change lead to particular health outcomes or demographic shifts, we need to think about how climate affects everyday realities. How does flooding alter the decision to have children? Does it change the availability of contraception, or damage the local economy?  

Effective interventions—policies that really build resilience to climate shocks—target those kinds of practical, mundane issues. And to design, study, and implement solutions that work, we must train students of global health to understand and assess them.  

“Big, Crazy Ideas” and Bold Responses 

Dr. Thiede closed his discussion with a call to action. Engineers have proposed wild, hugely ambitious solutions to rising sea levels, like buttressing ice shelves or draining the beds of glaciers. Sociologists and demographers, he said, need to do the same. We bear a responsibility to think in bold, big-picture terms about responses to the climate crisis.  

The session ended with an engaging back-and-forth about finding solutions and the future of the field. In response to questions from Dr. Ngo and audience members, Dr. Thiede offered a list of practical implications and take-home ideas based on his work.  

Key Takeaways: 

• We may have reached the limits of DHS data; global health and population science need a major investment in high-frequency data collection. 

• New research needs to focus more directly on solutions, testing scalable interventions and moving beyond descriptive methods. 

• “Climate is never the only stressor”—and our research needs to grapple with the mutually aggravating effects of armed conflict, social instability, and economic pressures.  

• We must change how we teach. The next generation of population scholars should be better prepared for the distinctively interdisciplinary complexities the field now faces.