Learning value of experiments versus immediate impact

Vaccines are remarkably effective at preventing deadly diseases, and, while global needs for them are great, vaccines already receive substantial global funding. This creates a challenge: How do you identify opportunities where additional funding can meaningfully increase vaccination rates and save lives?

GiveWell has long recognized the potential for highly cost-effective vaccine programs. We started supporting vaccination programs in 2015 and have made over $200 million in vaccination-related grants to date. For example, New Incentives, one of our Top Charities, aims to increase routine childhood vaccinations in northern Nigeria by providing small cash incentives to caregivers who bring their children into clinics for vaccinations. 

Over the past several years, we’ve been growing our research team and laying the groundwork to expand the scope of our work and funding. 

In this episode, GiveWell CEO and co-founder Elie Hassenfeld speaks with Senior Program Officer Natalie Crispin, who leads GiveWell’s vaccination grantmaking. They discuss how our research approach has evolved and what it means for helping more children access life-saving vaccinations.

Elie and Natalie discuss:

• Moving from finding existing programs to targeting funding gaps: In the past, GiveWell primarily looked for specific, evidence-backed program types to support—such as conditional cash transfers that incentivize vaccination. Now, with a dedicated vaccines team, we ask a bigger question: What are the bottlenecks that prevent children from getting vaccinated and how can we address them? This shift has driven our funding in areas like vaccination outreach, where teams travel to remote communities to deliver vaccines.
• Building a grantmaking portfolio to maximize learning: GiveWell recently funded several vaccination outreach programs. For example, in DRC’s Kongo Central province, where vaccination coverage rates are low, we’re supporting planning vaccination sessions (e.g. timing, frequency, location) with better data, paying community health workers to track which children need vaccines, and funding motorbikes and fuel for vaccination teams to provide vaccination near communities who are far from health facilities. This year, we hope to fund a number of additional vaccination outreach and mobile vaccination programs in differing contexts. We expect this will provide the opportunity to learn quickly about what works and help us direct future funding accordingly.
• Expanding capacity through specialization: Over the past three years, GiveWell’s research team has doubled in size and its structure has changed. Today, nearly 60 researchers work on cause-specific teams, one of which focuses on vaccination. This specialization has enabled deeper relationships with vaccination implementers, funders, and government officials—relationships that have allowed us to surface new opportunities and better understand potential funding gaps. 

GiveWell’s vaccination grantmaking is a longstanding area of focus with growing diversity and impact. The deepening expertise and novel approaches of that dedicated team illustrate how the research team as a whole has evolved to pursue opportunities we wouldn’t have been able to just a few years ago. With greater capacity and specialization across health areas, we’re now better positioned to identify and direct donations to highly cost-effective programs that save and improve lives.

Visit our Top Charities Fund and All Grants Fund pages to learn more about how you can support this work, and listen or subscribe to our podcast for our latest updates.

This episode was recorded on February 10, 2026 and represents our best understanding at that time.