Nobel Prize in Physiology or Medicine 2023
She was met with resistance, demoted and eventually forced to leave academia – but Katalin Karikó never lost focus, doubling-down on her work to harness mRNA for new vaccines and therapies. Karikó’s Nobel Prize-awarded discovery enabled the development of effective vaccines against COVID-19, offering protection to millions of people.
Born in 1955 in Szolnok, Hungary, Katalin Karikó grew up without running water, a TV or a family background in science. Nevertheless, in elementary school, she was already winning biology accolades, driven by her own curiosity and support from home.
“My parents encouraged us to study because they had no opportunity,” she said. However, not everyone was so supportive. One of her teachers told her he would make sure she did not go to university. Instead of giving up, Karikó worked harder.
In the chemistry laboratory at the Biological Research Center of the Hungarian Academy of Sciences. Szeged, 1980.
© University of Szeged Klebelsberg Library
Katalin Karikó with her husband Béla Francia and their daughter Susan by their first car, a Ford Pinto, a month after arriving in the United States. Philadelphia, Pennsylvania, 1985.
Credit: Katalin Karikó
Katalin Karikó and her husband Béla Francia celebrating their daughter, Susan, winning a gold medal in rowing at the Olympics. London, UK, 2012.
Credit: Katalin Karikó
After a summer school visit aimed at promising pupils whose parents were blue-collar workers, Karikó was accepted at the University of Szeged – a prestigious research hub in Hungary. “It was like winning the lottery,” she said.
She completed her PhD in biochemistry in 1982, before beginning her work with messenger RNA (mRNA), which helps the human genome coded in DNA to be read by the body’s cellular machinery. When her lab lost its funding, she decided to take the life-changing step of moving with her family to the US.
As Hungary’s Communist regime only permitted Karikó to take $100 out of the country, she sold her car on the black market and sewed the proceeds – a little more than $1,000 – into her two-year-old daughter’s teddy bear. She made the trip with husband and daughter, who would grow up to win two gold Olympic medals for the United States in rowing.
“It was a cultural shock. (…) going from Hungary today to there [the US] would be very different. But in 1985, it was unbelievable.”
Katalin Karikó
Karikó began work at Temple University where she was involved in clinical trials using RNA to treat patients with AIDS. She then joined the University of Pennsylvania in 1989 to work on mRNA, which at the time was largely dismissed as unstable and useless by the wider scientific community. She remained steadfast in her aim of turning mRNA into a medical therapy, making small discoveries, but struggled to secure funding. Despite being demoted, she persisted in her work, “working like nothing happened.”
She didn’t know that a chat at a photocopier would change her fortunes. During the late 1990s, Karikó met Drew Weissman, an immunologist with a PhD in microbiology trying to design better vaccines. The two researchers joined forces to harness mRNA and try to make a new type of vaccine capable of generating immunity without injecting a pathogen into the body. Being experts in different fields, Karikó and Weissman “were constantly educating each other,” she said.
Their initial experiments using synthetic mRNA in mice were discouraging. Harmful inflammatory immune responses caused the rodents to become sick and sometimes die. After years investigating the cause of the inflammation and how to prevent it – curiously, in separate labs – Karikó and Weissman made a breakthrough.
When the duo modified the bases of mRNA, they found that the unwanted inflammatory reactions were successfully blocked, while the production of desired proteins was increased. “We realised at that moment that this would be very important, and it could be used in vaccines and therapies,” said Karikó.
She and Weissman thought their discovery would attract considerable attention after it was published in 2005. “We thought the phone would be ringing off the hook. But nothing happened. The phone didn’t ring. Nobody cared.”
Instead, their work was met with disbelief. In 2013, Karikó hit rock bottom when she was forced to retire, after her university refused to reinstate her former position. “They told me that they’d had a meeting and concluded that I was not of faculty quality,” she said.
“I was kicked out from Penn after 24 years. No goodbye party, nothing, just get out. I walked to the parking lot, thinking what next?”
Katalin Karikó
Another chapter began for Karikó, who decided to join the biopharmaceutical company BioNTech, which led to her travelling between Germany and the US for a decade. Despite the long commute, she enjoyed performing experiments herself and working towards a shared goal to develop a therapeutic product. “It was more meaningful than more paperwork and more references,” she said.
In early 2020, COVID-19 began sweeping across the world and scientists scrambled to develop a vaccine to protect the global population. Now, the time had finally come for the work done by Karikó and Weissman decades earlier. Scientists took their modified mRNA template and used it together with the virus genetic sequence shared by China to design a vaccine. The new COVID-19 vaccine could be delivered remarkably quickly, offering hope and protection to millions of people. The hard work that Weissman and Karikó put in had finally paid off.
A letter from a retirement home helped Karikó understand the difference her work had made. When a resident tested positive, everyone worried one third of elderly group would die, but having been vaccinated a week before, they all lived and celebrated Katalin Karikó with a party, sending her photos of the happy occasion. “I can tell you that it was more important than any award, including the Nobel Prize, reading that letter, seeing those pictures,” she said.
“I never had this craving for recognition. For me, it's enough that I know what I did.”
Katalin Karikó
The COVID-19 vaccine is estimated to have averted 2.5 million deaths between 2020 and 2024. Its underlying technology, pioneered by Karikó and Weissman, is being developed to prevent other infectious diseases, and as a cancer treatment. Having previously struggled to secure research grants, Karikó returned to her first university of Szeged and used prize money to fund RNA research and support the next generation of scientists continuing her work.
In 2023, she shared the Nobel Prize in Physiology or Medicine with Weissman and took the opportunity to thank scientists who paved the way for her work. She later said: “I also thank the people who tried to make my life miserable because they made me work harder and become more resilient.”
