A boy who wanted to fix things
Drew Weissman was born on September 7, 1959, in Lexington, Massachusetts, and grew up in a middle-class household, his father an engineer, his mother a dental hygienist. He was a quiet, methodical child, the kind who took apart radios and clocks to understand them. At the age of five he was diagnosed with type 1 diabetes, then managed with glass syringes and boiled needles. Living inside a chronic illness, and depending on a medical advance, insulin, that had been discovered only decades before, gave him an early and personal sense of what research could do for an ordinary life. He has said he never seriously considered another path. He studied biochemistry as an undergraduate at Brandeis University, drawn less to the glamour of medicine than to its mechanisms, to the molecular machinery that, understood well enough, might be redirected to heal.
Becoming a physician-scientist
Weissman pursued the long, demanding training of a physician-scientist, earning both an MD and a PhD in immunology from Boston University in 1987. He completed a residency in Boston and then spent several years at the National Institutes of Health, working in the laboratory of Anthony Fauci on HIV and on dendritic cells, the immune system’s sentinels, which detect threats and instruct the body’s defenses. That work shaped the question that would define his career: if you could speak to the immune system directly, in a language it understood, you could in principle train it against almost anything. In 1997 he moved to the University of Pennsylvania to set up his own laboratory and pursue exactly that idea. He was not, at that point, a famous scientist, and the avenue he had chosen was one most of his field considered a dead end.
A meeting at the photocopier
The collaboration that changed medicine began, by both their accounts, beside a photocopier. Katalin Karikó was a Hungarian-born biochemist at Penn, brilliant and stubborn, who had staked her career on messenger RNA, the molecule that carries genetic instructions from DNA to the cell’s protein factories. Her conviction was that synthetic mRNA could make the body manufacture its own medicine. The field disagreed: funding agencies rejected her grants, and Penn had demoted her and cut her pay. Weissman, newly arrived and looking for a way to make better vaccines, fell into conversation with her over the copier and recognized the promise that others had dismissed. They began to work together, an immunologist who wanted a delivery system and a biochemist who had one almost no one believed in. For years they would be, in Weissman’s words, two scientists scarcely anyone was paying attention to.
The problem with mRNA
The reason mRNA had stalled as a medicine was brutal and specific. When synthetic mRNA was injected into an animal, the body treated it as an invader: the immune system attacked it, inflammation flared, and the mRNA was destroyed before it could do its work. To many researchers this looked fatal. Weissman and Karikó instead treated it as a puzzle. Why did the body’s own mRNA pass unnoticed while laboratory-made mRNA set off alarms? They worked through the chemistry of the molecule piece by piece, comparing natural and synthetic versions, hunting for the difference that triggered the immune response. It was painstaking, unglamorous laboratory work, sustained year after year on thin funding and with little outside interest, the kind of slow, uncertain research that modern science often struggles to support, and that nonetheless underlies many of its greatest advances.
The 2005 breakthrough
In 2005 they found the answer and published it. The key lay in the building blocks of RNA, the nucleosides. By swapping one natural nucleoside for a subtly modified version, pseudouridine, they could make synthetic mRNA effectively invisible to the immune system’s alarms, while leaving it fully able to instruct cells to build proteins. It was an elegant and decisive solution to the problem that had blocked the entire field. And it was almost entirely ignored. The paper appeared in a respected journal, drew few citations, and changed no one’s plans overnight. Weissman and Karikó kept working, refining the chemistry, and developing ways to package mRNA inside tiny fat bubbles, lipid nanoparticles, so it could reach cells intact. The world had been handed a key to a new kind of medicine, and for the better part of a decade, scarcely anyone noticed.
From obscurity to the edge of everything
Slowly, the right people noticed. The modified-mRNA technology was licensed, and it became the scientific foundation of two biotechnology companies, BioNTech in Germany and Moderna in the United States, both betting that mRNA could be turned into vaccines and therapies. Through the 2010s they worked on mRNA approaches to influenza, Zika, and other diseases, building manufacturing know-how and refining the lipid nanoparticles that carried the molecule. The science was maturing in relative quiet, still far from a household name. Weissman continued his research at Penn; Karikó eventually joined BioNTech as a senior executive. The platform they had spent twenty years building was, by the end of the decade, technically ready, a general method for instructing human cells, waiting for a problem urgent enough to prove it at scale. In late 2019, that problem arrived.
The vaccines
When the genetic sequence of the new coronavirus was published in January 2020, the mRNA approach showed its single greatest advantage: speed. Because an mRNA vaccine needs only the genetic code of a target protein, not the virus itself, Moderna and BioNTech were able to design vaccine candidates within days. Built directly on Weissman and Karikó’s modified-nucleoside chemistry and the lipid-nanoparticle delivery system, the two vaccines proved in large trials to be roughly 95 percent effective, a result that startled even optimists. By the end of 2021 they had been administered billions of times across the world. A 2022 study in The Lancet Infectious Diseases estimated that COVID-19 vaccines saved roughly 20 million lives in their first year alone. A discovery that had languished, unread, for fifteen years had become, almost overnight, one of the most consequential medical interventions in history.
The Nobel, and a vindication
In October 2023, Drew Weissman and Katalin Karikó were awarded the Nobel Prize in Physiology or Medicine, for the discoveries concerning nucleoside base modifications that enabled effective mRNA vaccines. For Karikó in particular, demoted, defunded, and dismissed for much of her career, the prize was a profound public vindication, and the two scientists’ long partnership became a widely told story about persistence, and about the danger of a research system that rewards only fashionable work. Weissman, characteristically, deflected much of the attention toward the science and the larger community of researchers who had contributed. The honors that followed, and there were many, mattered to him chiefly, he suggested, because they drew resources and talent toward a technology he believed was only beginning to show what it could do.
A scientist, not a celebrity
Even after the Nobel Prize, Weissman remained, by temperament, a working scientist rather than a public figure. He kept his laboratory at the University of Pennsylvania, kept seeing the research through, and consistently turned interviews back toward the science and toward the many colleagues whose work the vaccines also rested on. Friends and colleagues describe a calm, understated man, more comfortable at the laboratory bench than on a stage. His own type 1 diabetes, diagnosed when he was five, had given him a lifelong and personal understanding of what it means to depend on medical research, and a corresponding impatience with anything that slowed it down. He has been an outspoken critic of a funding culture that, for two decades, dismissed the very work that would later save millions, and an advocate for the sustained support of unfashionable basic research. The lesson he draws from his own career is not about brilliance but about endurance: that the discoveries which matter most are often the ones that look, for years, as though they are going nowhere.
A platform for the future
The deeper significance of Weissman’s work is that mRNA is not one vaccine but a platform, a reprogrammable way of instructing the body’s own cells to make almost any protein on command. Researchers are now pursuing mRNA vaccines and therapies for influenza, HIV, malaria, certain cancers, and rare genetic diseases; Weissman’s own laboratory has worked on a low-cost vaccine approach aimed at the developing world. If even a fraction of that promise is realized, the quiet discovery made at a Philadelphia laboratory bench in 2005 will rank among the most important of the century. It is also a lesson in how science actually advances: not only through sudden genius, but through patient, unfashionable, often unfunded work, sustained by people stubborn enough to keep going when almost no one is watching.
Sources & further reading
Drew Weissman, Wikipedia · Researched from the sources above and checked against them. Spotted an error? Tell us.
A life of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.