“It’s going to be transforming,” Dr. Fauci said of mRNA research. “It is already transforming for Covid-19, but also for other vaccines. H.I.V. — people in the field are already excited. Influenza, malaria.”

For Dr. Kariko, most every day was a day in the lab. “You are not going to work — you are going to have fun,” her husband, Bela Francia, manager of an apartment complex, used to tell her as she dashed back to the office on evenings and weekends. He once calculated that her endless workdays meant she was earning about a dollar an hour.

For many scientists, a new discovery is followed by a plan to make money, to form a company and get a patent. But not for Dr. Kariko. “That’s the furthest thing from Kate’s mind,” Dr. Langer said.

She grew up in the small Hungarian town of Kisujszallas. She earned a Ph.D. at the University of Szeged and worked as a postdoctoral fellow at its Biological Research Center.

In 1985, when the university’s research program ran out of money, Dr. Kariko, her husband, and 2-year-old daughter, Susan, moved to Philadelphia for a job as a postdoctoral student at Temple University. Because the Hungarian government only allowed them to take $100 out of the country, she and her husband sewed £900 (roughly $1,246 today) into Susan’s teddy bear. (Susan grew up to be a two-time Olympic gold medal winner in rowing.)

When Dr. Kariko started, it was early days in the mRNA field. Even the most basic tasks were difficult, if not impossible. How do you make RNA molecules in a lab? How do you get mRNA into cells of the body?

Universities only support low-level Ph.D.s for a limited amount of time, Dr. Langer said: “If they don’t get a grant, they will let them go.” Dr. Kariko “was not a great grant writer,” and at that point “mRNA was more of an idea,” he said.

But Dr. Langer knew Dr. Kariko from his days as a medical resident, when he had worked in Dr. Barnathan’s lab. Dr. Langer urged the head of the neurosurgery department to give Dr. Kariko’s research a chance. “He saved me,” she said.

Dr. Langer thinks it was Dr. Kariko who saved him — from the kind of thinking that dooms so many scientists.

Working with her, he realized that one key to real scientific understanding is to design experiments that always tell you something, even if it is something you don’t want to hear. The crucial data often come from the control, he learned — the part of the experiment that involves a dummy substance for comparison.

“There’s a tendency when scientists are looking at data to try to validate their own idea,” Dr. Langer said. “The best scientists try to prove themselves wrong. Kate’s genius was a willingness to accept failure and keep trying, and her ability to answer questions people were not smart enough to ask.”

Dr. Langer hoped to use mRNA to treat patients who developed blood clots following brain surgery, often resulting in strokes. His idea was to get cells in blood vessels to make nitric oxide, a substance that dilates blood vessels, but has a half-life of milliseconds. Doctors can’t just inject patients with it.

He and Dr. Kariko tried their mRNA on isolated blood vessels used to study strokes. It failed. They trudged through snow in Buffalo, N.Y., to try it in a laboratory with rabbits prone to strokes. Failure again.

Leading scientific journals rejected their work. When the research finally was published, in Immunity, it got little attention.

Dr. Weissman and Dr. Kariko then showed they could induce an animal — a monkey — to make a protein they had selected. In this case, they injected monkeys with mRNA for erythropoietin, a protein that stimulates the body to make red blood cells. The animals’ red blood cell counts soared.

“We talked to pharmaceutical companies and venture capitalists. No one cared,” Dr. Weissman said. “We were screaming a lot, but no one would listen.”

Eventually, though, two biotech companies took notice of the work: Moderna, in the United States, and BioNTech, in Germany. Pfizer partnered with BioNTech, and the two now help fund Dr. Weissman’s lab.

The vaccines, though, needed a lipid bubble to encase the mRNA and carry it to the cells that it would enter. The vehicle came quickly, based on 25 years of work by multiple scientists, including Pieter Cullis of the University of British Columbia.

Scientists also needed to isolate the virus’s spike protein from the bounty of genetic data provided by Chinese researchers. Dr. Barney Graham, of the National Institutes of Health, and Jason McClellan, of the University of Texas at Austin, solved that problem in short order.

Dr. Weissman celebrated with his family, ordering takeout dinner from an Italian restaurant, “with wine,” he said. Deep down, he was awed.

This content was originally published here.