The adage that necessity is the mother of invention rang true in this year’s Nobel Prize for Medicine when Hungarian scientist Katalin Kariko and U.S. colleague Drew Weissman made mRNA molecule discoveries that paved the way for COVID-19 vaccines that were rolled out in record time during the pandemic crisis. They are now credited with “contributing to the unprecedented rate of vaccine development during one of the greatest threats to human health in modern times,” the Nobel award-giving body said in its 2023 accolade for the pair, announced on Monday.

The researchers, who are both professors at the University of Szeged in Hungary and adjunct professors at UPenn’s Perelman School of Medicine in Philadelphia (UPenn), had been working for years to make labmade messenger RNA (mRNA) work as vaccines by directing cells to make specific proteins. They showed in the early 2000s that mRNA could be dampened from triggering an unwanted immune response by making specific changes to the component bases of the molecules. This allowed for the development of mRNA-based vaccines that can be delivered to the immune system with minimal side effects.

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But the research had been fraught with roadblocks. The pair struggled to raise funds, and Kariko spent most of the 1990s applying for grants to translate their hypotheses into experiments showing mRNA worked. She was demoted at Penn and had to sell her car to stay afloat, but she persevered. She eventually met Weissman, an immunologist who had joined the faculty at Penn after a fellowship at the National Institutes of Health, and struck up a collaboration. They would go on to publish their critical paper in 2005.

Weissman and Kariko were the first to show that mRNA could be delivered into cells without triggering an unwanted immune response, and their findings enabled a subsequent surge in mRNA-based vaccine developments. The researchers have shared this year’s Nobel prize jointly because of the complementary nature of their work, with Kariko bringing deep expertise in mRNA and Weissman possessing a unique perspective on the immune system and how it reacts to vaccines.

Their discovery triggered a new era in vaccinations, and their ideas are now being applied to mRNA-based vaccines against other viruses, including influenza, genital herpes, and cancer, the Nobel committee said. In addition to their Nobel, the pair has been honored by many other awards, including a Lewis S. Rosenstiel award and a Breakthrough Prize from the Breakthrough Foundation, and Columbia University awarded them the Louisa Gross Horwitz prize. They will receive their prizes, consisting of a gold medal and a $1 million cheque, at a ceremony in Stockholm on December 10, the anniversary of Alfred Nobel’s death in 1896. They will be the 13th pair of women to win the prize. They also have won a coveted spot on the Forbes 30 under 30 list of innovators in biomedicine and technology. The Nobel Committee said that the pair’s mRNA-based vaccines have been administered more than 13 billion times and saved millions of lives.