Today, the Nobel Assembly at Karolinska Institutet announced that the Nobel Prize in medicine was awarded to Katalin Karikó and Drew Weissman “for their discoveries concerning nucleoside base modifications that enabled the development of effective mRNA [messenger RNA] vaccines against COVID-19.”  Dr. Karikó is a Professor at Szeged University and an Adjunct Professor at Perelman School of Medicine at the University of Pennsylvania.  Dr. Weissman is the Roberts Family Professor in Vaccine Research and Director of the Penn Institute for RNA Innovations.

According to the Nobel Assembly, that research by Karikó and Weissman laid the foundation for development of mRNA vaccines for COVID-19.  Before the COVID-19 pandemic, vaccines were based on:  (1) killed or weakened viruses, like the polio, measles, and yellow fever vaccines; (2) using parts of viral genetic code that encodes proteins on the virus surface to stimulate formation of virus-blocking antibodies, like the vaccines against hepatitis B and human papillomavirus; or (3) putting parts of the viral genetic code in a harmless carrier virus, known as a vector, like in the Ebola virus vaccine.  The Nobel Assembly reported that each of these methods requires large-scale cell culture, which limits the possibility for rapid vaccine production and that while messenger RNA vaccines had also been studied (prior to the work of Karikó and Weissman), the use of in vitro (non-cell culture) methods for transcribing mRNA resulted in mRNA that was difficult to deliver and often caused inflammatory responses.

The Nobel Assembly explained that “Karikó and Weissman showed that the delivery of mRNA generated with base modifications markedly increased protein production compared to unmodified mRNA. …  Through their discoveries that base modifications both reduced inflammatory responses and increased protein production, Karikó and Weissman had eliminated critical obstacles on the way to clinical applications of mRNA” which allowed mRNA vaccines encoding the SARS-CoV-2 surface protein to be developed at “record speed.”

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