Against all odds

The first time I encountered Pardis Sabeti, I did not know her name and did not particularly care to. I was a freshman in high school, and some required class had assigned a series of statistics videos from Annenberg Learner, the kind of public-television courseware that arrives in your life with all the glamour of a fire-safety filmstrip. The series was called Against All Odds: Inside Statistics. I remember stemplots and standard deviations and a host who seemed a little too sincerely delighted by histograms of lightning strikes. What I did not register, because I had no reason to, was that the host walking me through two-way tables ran outbreak science for a living, and that she had built one of those tutorials out of her own research into genetic resistance to Lassa fever in West Africa. She filmed those lectures in 2013, the year before the largest Ebola outbreak on record, and by the time the assignment reached me she had already lived through it. I sat through a full unit of her explaining inference without the faintest idea that the host had spent the intervening years at the center of an epidemic.

I learned all of that much later, and in pieces. Sabeti is a computational geneticist at the Broad Institute and Harvard who built her early reputation on statistical tests for detecting natural selection in the human genome, then turned those methods on the pathogens that select us in return. She also fronts a rock band, which is the sort of detail that makes more sense once you have watched her teach probability with the energy of someone who genuinely cannot believe how interesting it all is. What I find most instructive about her, more than any single line in her bibliography, is that she trained as a physician and then declined to choose between the clinic and the computer, treating medicine and computation as one practice rather than two careers to pick between.

The outbreak itself I came to through a film. FRONTLINE’s Outbreak, directed by Dan Edge and aired in 2015, remains one of my favorite documentaries, which is a strange thing to say about ninety minutes of nearly unbroken grief. It traces the 2014 epidemic from a one-year-old boy in a Guinean village to the wards of Sierra Leone and the slums of Monrovia, and its central question is not how the virus killed but why the response failed for so long. Much of it takes place at Kenema Government Hospital, where the government chose to treat Ebola patients because Kenema already ran a ward for Lassa fever, a related hemorrhagic disease. Within days the caseload outran the ward, and then the nurses began to die. The deputy head nurse, Josephine Sellu, describes counting bodies in the morgue and wondering whether the world was ending. Thirty-seven health workers died at that one hospital: doctors, nurses, porters, cleaners, security guards, lab technicians. Word went around town that doctors had invented Ebola to steal blood, and crowds threw stones at the building and threatened to burn it down. The film closes by reading the names of the dead aloud, nurses and lab techs and small children. It never converts any of that into a lesson, and the refusal is why I have not been able to put it down.

Here is where the statistics videos and the documentary close into a single circuit. The Lassa fever program at Kenema, the one featured in that tutorial I half-watched at fourteen, was Sabeti’s foothold in Sierra Leone for years before Ebola arrived. When the outbreak came, that program and its people became the front line. In August 2014 her lab published ninety-nine Ebola genomes drawn from seventy-eight patients at Kenema in Science, work that let researchers track in something close to real time how the virus was moving and mutating across West Africa. They released the sequences immediately, before the paper was even written, on the conviction that hoarding data during an epidemic is its own form of harm. By the time the paper appeared, five of its co-authors had died of the disease they had helped to sequence: Mohamed Fullah, Mbalu Fonnie, Alex Moigboi, Alice Kovoma, and Sheik Humarr Khan, the physician who led the Kenema program and whom Sabeti named as a co-senior author and a friend. The data and the dying were never two separate stories. The genomes came from the same ward, gathered by the same hands, that the outbreak was steadily emptying.

I think about that circuit often, because the lesson of it is easy to state and hard to live by. An outbreak in a remote district is never a local event for long. The same connective tissue that moves people and goods moves pathogens, and a virus that goes unseen in one place for a few weeks can be on three continents by the time anyone gives it a name. Heroics rarely decide whether an outbreak stays local. The scaffolding does, and somebody has to put it up years ahead of the need: surveillance that catches an anomaly early, laboratories that can confirm it, clinicians and data systems already in place when the first patient walks in. That scaffolding costs money, photographs badly, and in the long stretches between emergencies it is the first line a budget cuts. Even after COVID, the field expects more of these, not fewer. The closing argument of Outbreak, delivered by the WHO’s Bruce Aylward, was that Ebola was not an exception but a precedent, and that more of these are coming whether we are ready or not.

The lesson I take from 2014 is not the one the genre usually wants to sell. The telling almost always turns on who arrived. What settled this one was already standing. I am instinctively skeptical that good intentions routed through large institutions reliably reach the ward, and the history here does little to soften that skepticism. The things that carried weight, nobody had built for an audience: a Lassa ward that already existed, a surveillance system someone funded the year before anyone was watching, a sequencing pipeline ready to run, a team that knew the terrain. Sabeti released the genomes the moment they existed, which is the same ethic in a different form. So was Khan’s clinic. The dramatic part of an outbreak is almost never the part that decides how it ends.

I think about those statistics videos more than I expected to. The doctor I barely registered at fourteen had filmed them just before the outbreak that would take the lives of several of her colleagues and reshape her own, and she was walking me cheerfully through two-way tables using the very Lassa research that would soon put her at the center of it. By the time the assignment reached me, all of it had already happened, and I knew none of it. That is the part I keep returning to. The people whose work decides how an outbreak ends rarely look, at the time, like they are doing anything momentous. They are building the quiet, durable things in the years when no one is watching. I am grateful, in a roundabout way, to whatever teacher made me watch.