Katalin "Kati" Karikó (born 17 January 1955) is a Hungarian and American biochemist who specializes in ribonucleic acid (RNA)-mediated mechanisms, particularly in vitro-transcribed messenger RNA (mRNA) for protein replacement therapy. Karikó laid the scientific groundwork for mRNA vaccines, overcoming major obstacles and skepticism in the scientific community. Karikó received the Nobel Prize in Physiology or Medicine in 2023 for her work, along with American immunologist Drew Weissman.
Karikó co-founded and was CEO of RNARx from 2006 to 2013. From 2013 to 2022, she was associated with BioNTech RNA Pharmaceuticals, first as a vice president and promoted to senior vice president in 2019. In 2022, she left BioNTech to devote more time to research. In 2021, she received an honorary doctorate from the University of Szeged in Hungary, where she has since become a professor. While Karikó has also been associated with the University of Pennsylvania, which would benefit financially from her eventual discovery, the university had actively discouraged her from pursuing research by underfunding and deprioritizing work on mRNA. After being demoted by the University of Pennsylvania in 1995, Karikó was never granted tenure and joined BioNTech in 2013 after the university had declined to reinstate her.
Karikó's work includes scientific research on RNA-mediated immune activation, resulting in the co-discovery with Drew Weissman of the nucleoside modifications that suppress the immunogenicity of RNA. This is seen as a further contribution to the therapeutic use of mRNA. Together with Weissman, she holds United States patents for the application of non-immunogenic, nucleoside-modified RNA. This technology has been licensed by BioNTech and Moderna to develop their protein replacement technologies, but it was also used for their COVID-19 vaccines.
The messenger RNA-based technology developed by Karikó and the two most effective vaccines based on it, BioNTech/Pfizer and Moderna, formed the basis for the effective and successful fight against SARS-CoV-2 virus worldwide and contributed significantly to the containment of the COVID-19 pandemic. For their work, Karikó and Weissman have received numerous other awards besides the Nobel, including the Lasker–DeBakey Clinical Medical Research Award, Time Magazine's Hero of the Year 2021, and the Tang Prize Award in Biopharmaceutical Science in 2022.
Early life and education
Katalin Karikó was born in Szolnok, and grew up in Kisújszállás, Hungary, in a small home without running water, a refrigerator, or television. Her father János was a butcher, and her mother was a bookkeeper. Her father was punished for participating in the revolt of 1956. She excelled in science during her primary education, earning third place in Hungary in a biology competition.
A 2024 retrospective by the University of Szeged further documents Karikó's upbringing in Kisújszállás, Hungary, where her early passion for chemistry and biology was nurtured through academic competitions, achieving top national rankings by eighth grade. This foundation is recognized as a key influence on her later breakthroughs in mRNA research.…
Karikó obtained a BSc degree in biology in 1978 and her PhD in biochemistry in 1982, both from the University of Szeged. She worked with Jenő Tomasz and continued her postdoctoral research at the Institute of Biochemistry, Biological Research Centre (BRC) of Hungary. From 1978 until 1985, she was listed as an intelligence asset by the Communist Hungarian secret police, something she says she was blackmailed into out of fear of repercussions on her career or reprisals against her father. She claims that she did not provide them with information nor was she active as an agent.
In 1985, her lab at the BRC lost its funding, and Karikó sought work at institutions in other countries. After being offered a research position by Robert J. Suhadolnik of Temple University, Karikó left Hungary for the United States with her husband and two-year-old daughter, carrying her daughter's teddy bear stuffed with £900 that they had received from selling their car and exchanging currency on the black market.
Career Between 1985 and 1988, Karikó was a postdoctoral fellow at Temple University in Philadelphia. Karikó participated in a clinical trial in which patients with AIDS, hematologic diseases, and chronic fatigue syndrome were treated with double-stranded RNA (dsRNA). This was considered groundbreaking research, as the molecular mechanism of interferon induction by dsRNA was not known, although the antiviral and antineoplastic effects of interferons were well-documented.
In 1988, Karikó accepted a job at Johns Hopkins University without first informing her lab advisor Suhadolnik of her intention to leave Temple, as recounted in Gregory Zuckerman's 2021 book A Shot to Save the World. Suhadolnik told her that if she went to Johns Hopkins, he would have her deported, and subsequently reported her to U.S. immigration authorities, claiming that she was "illegally" in the United States. In the time it took her to successfully challenge the resulting extradition order, Johns Hopkins withdrew the job offer. Suhadolnik "continued bad-mouthing Karikó, making it impossible for her to get a new position" at other institutions, until she met a researcher at Bethesda Naval Hospital who "had his own difficult history with Suhadolnik".A Shot to Save the World: The Inside Story of the Life-or-Death Race for a COVID-19 Vaccine ; p. 69; by Gregory Zuckerman; published 26 October 2021, by Penguin Books Karikó subsequently confirmed that the incident had happened as Zuckerman described, but emphasized that "more importantly I was always grateful to [Suhadolnik for] sending me the IAP66 form in 1985, for the opportunity he gave me to work in his lab", noting that "when I gave a lecture [at Temple, a] couple of years later, I thanked him for the science I learned from him."Part one: The true story of the COVID-19 vaccines , by Rick Morton, in The Saturday Paper; published 11 December 2021 (no. 379); retrieved 4 October 2023 From 1988 to 1989, she worked at the Uniformed Services University of the Health Sciences in Bethesda, Maryland where she worked with signal protein interferons.
In 1989, she was hired by the University of Pennsylvania to work with cardiologist Elliot Barnathan on messenger RNA (mRNA). In 1990, while an adjunct professor at the Perelman School of Medicine at the University of Pennsylvania, Karikó submitted her first grant application in which she proposed establishing mRNA-based gene therapy. Ever since, mRNA-based therapy has been Karikó's primary research interest. However, in the 1990s, mRNA fell out of favor as many researchers, biotechs, and pharmaceutical companies doubted its potential. Though supported by Elliot Barnathan (who left UPenn in 1997) and David Langer (who then hired her), Karikó found it difficult to gain funding. She was initially on track to become a full professor, but after repeated grant rejections the university demoted her in 1995. Nevertheless, she chose to remain and continue her mRNA research.
In 1997, she met Drew Weissman, a professor of immunology who had recently arrived at the University of Pennsylvania. They began to exchange ideas and then to collaborate. Weissman's funding was critical in helping Karikó to continue and extend her research and the combination of Weissman's immunology and Karikó's biochemistry was extremely effective. They began to move the technology forward, solving problems one at a time, and eventually gaining recognition. Weissman has commented "We had to fight the entire way." Karikó's persistence was noted as exceptional against the norms of academic research work conditions.
Before 2005, a major problem with the proposed therapeutic use of mRNA was that in vivo use led to inflammatory reactions. A key insight came about when Karikó focused on why transfer RNA (tRNA), used as a control in an experiment, did not provoke the same immune reaction as mRNA. A series of landmark studies beginning in 2005 demonstrated that while synthetic mRNA was highly inflammatory, tRNA was noninflammatory. Karikó and Weissman determined how specific nucleoside modifications in mRNA led to a reduced immune response: by replacing uridine with pseudouridine. Their key finding of a chemical modification of mRNA to render it non-immunogenic was rejected by the journals Nature and Science, but eventually accepted by the publication Immunity.
Another important achievement by the researchers was the development of a delivery technique to package the mRNA in lipid nanoparticles, a novel pharmaceutical drug delivery system for mRNA. The mRNA is injected into tiny fat droplets (lipid nanoparticles) which protect the fragile molecule until it can reach the desired area of the body. They demonstrated its effectiveness in animals.
Karikó and Weissman founded a small company, RNARx, and in 2006 and 2013 received patents for the use of several modified nucleosides to reduce the antiviral immune response to mRNA. Soon afterward, the University of Pennsylvania sold the intellectual property license to Gary Dahl, the head of a lab supply company that eventually became Cellscript. Weeks later, Flagship Pioneering, the venture capital company backing Moderna, contacted her in an attempt to license the patent, at which point Karikó had to tell them it was no longer available.
In 2006, Katalin Karikó reached out to biochemist Ian MacLachlan to work with him on the chemically altered mRNA. Initially, MacLachlan and Tekmira turned away from the collaboration. Karikó wanted to team up with Ian MacLachlan because he was the leader of a team that helped advance mRNA technology. Karikó was working on establishing the formulated lipid nanoparticle delivery system that encapsulates mRNA in a dense particle through a mixing process.
In early 2013, Karikó heard of Moderna's $240 million deal with AstraZeneca to develop a Vascular endothelial growth factor mRNA. Karikó realized that she would not get a chance to apply her experience with mRNA at the University of Pennsylvania, so she took a role as vice president at BioNTech RNA Pharmaceuticals (and subsequently became a senior vice president in 2019), while maintaining an adjunct professorship at the university.
During Nobel Week 2023, Karikó remarked in an interview, "I dreamt about doing research, not getting an award," emphasizing her lifelong dedication to discovery over recognition and the central role of perseverance in her scientific path.
In November 2024, Karikó returned to Temple University's Hill College House and delivered a public lecture recounting her Nobel Prize experience including the iconic early morning notification and encouraging students to pursue research with persistence and enthusiasm.
Then in May 2025, Karikó delivered the prestigious Mendel Lecture at the European Society of Human Genetics Annual Meeting, where she discussed clinical applications of mRNA therapeutics and reflected on the collaborative efforts that enabled rapid COVID‑19 vaccine development.
As of October 2023, Karikó is a professor at University of Szeged in Hungary.
Scientific contributions Karikó's research and its specializations have a broad impact with potential implications for areas such as the generation of pluripotent stem cells, and messenger RNA-based gene therapy, as well as "a new class of drugs".