Nearly two decades ago, researchers at Harvard and the Broad Institute noticed something odd about diseases like Ebola and Lassa fever. These weren't new pathogens emerging from nowhere — genetic evidence suggested they'd circulated among humans for thousands of years. What was actually emerging was our ability to see them. Medicine had finally developed the tools to diagnose and track what had always been there.
That insight became the foundation for Sentinel, a disease surveillance network that just received a lifeline: a $100 million grant from the MacArthur Foundation in November. The funding arrived at a critical moment. Sentinel had been bleeding federal support and facing possible closure.
"Work in pandemic preparedness is having an existential crisis right now," said Pardis Sabeti, a Harvard professor and Sentinel co-founder. "We were really on a precarious ledge. So this has completely changed everything."
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Sabeti's path to this work began with genetics. As an MIT undergraduate, her adviser Eric Lander showed her how to read DNA as mathematical code. Years later, after earning a Rhodes scholarship and Ph.D. from Oxford, she noticed something striking: the Yoruba people of Nigeria carried genetic signatures of natural selection in a gene called LARGE — the exact same gene targeted by Lassa virus. This meant the virus hadn't just arrived recently. It had been circulating for millennia, and local populations had evolved resistance to it.
When Sabeti shared this discovery with Christian Happi, a Nigerian researcher who'd studied malaria in the same region, they recognized an opportunity. As a child, Happi had promised his mother he'd find a cure for the diseases that plagued his country. Now, with evidence that ancient pathogens were finally detectable, he and Sabeti could actually do something about it.
They set up a field site in rural Nigeria to study Lassa fever. What they found was sobering. At a hospital in the epicenter of an outbreak, staff diagnosed cases by looking at the color of blood plasma samples. There was no real diagnostic infrastructure.
The team designed a molecular test for Lassa virus and deployed it in 2008, training local health workers to run it. The impact was immediate. "The introduction of that test alone actually changed the paradigm in that community," Happi said. "They were able to diagnose people earlier, they were able to save more lives. The fatality rate dropped from 90% to 23.6%."
Building a System That Works
By 2013, Happi and Sabeti had established the African Center of Excellence for Genomics of Infectious Disease at Redeemer's University in Nigeria. Then the 2014 Ebola epidemic hit. In Sierra Leone, their team diagnosed the first case in the country. In Nigeria, Happi led the national response. Nigeria's aggressive contact tracing and community outreach — more than 18,000 face-to-face visits — contained the virus in 62 days. Out of a population of 230 million, there were only 20 cases and 8 deaths.
"That was the first demonstration that if you deploy a system like Sentinel it works," Happi said.
Launched in early 2020 — just as COVID-19 became a pandemic — Sentinel has now trained about 3,000 health personnel across nearly every African country. The network has administered more than 300,000 diagnostic tests and sequenced roughly 17,800 viral samples. They've developed cheap paper strips that detect viruses in the field and cloud-based platforms that let health workers coordinate responses in real time.
But the greatest threat came not from pathogens but politics. Federal funding from the CDC, NIH, and USAID dried up. Sentinel cut staff and faced an uncertain future.
The MacArthur grant changes that calculus entirely. The organization will now expand from Nigeria and Sierra Leone into Senegal, Rwanda, and the Democratic Republic of the Congo. "If you look at the magnitude of the work that should be done, you realize that $100 million is not a lot of money," Happi said. "But it can be used to steer things in the right direction and spark a bigger movement."
The real test comes next: whether a disease surveillance system built on the ground in Africa can catch the next outbreak before it becomes the next pandemic.
