The Nobel Assembly awarded its 2023 prize in Physiology or Medicine Monday to two scientists who made inroads in the development of the Covid vaccine. Katalin Karakó and Drew Weissman, who have each worked on messenger RNA research for decades, enabled vaccine production to occur in less than a year from the date at which work began.

Historically, the issue with mRNA vaccines has been that the immune system mistakes the molecule for an invading pathogen, attacking it and causing illness within the host before eventually destroying the mRNA. Karakó and Weissman discovered that, with a chemical modification, cells would protect their own mRNA.

The Nobel Assembly said the discovery “fundamentally changed our understanding of how mRNA interacts with our immune system” and “contributed to the unprecedented rate of vaccine development during one of the greatest threats to human health in modern times.”

The new approach to vaccinations was not initially accepted by the majority of scientists. In fact, according to the New York Times, a 2005 study Karakó and Weissman authored together was rejected by top-flight journals like Nature and Science, and eventually published by niche outlet Immunity. After their work went public, biotech companies Moderna and BioNTech — where Karikó serves as senior vice president — began to look into research on mRNA vaccines. Their practical use had not been considered in full until the coronavirus pandemic began in the early months of 2020.

Scientists believe the developments Karakó and Weissman kickstarted have the potential to one day inoculate humans against diseases like cancer that currently have no known cure. In fact, in May 2023, a group of scientists building on this mRNA work reported a vaccine against pancreatic cancer instigated an immune response in half of patients treated, and those who showed such a response did not endure a relapse of their cancer over the course of the study.