Katalin Kariko and Drew Weissman won the Nobel Prize in physiology or medicine on Monday for their discoveries related to nucleoside base modifications that enabled the development of mRNA vaccines against COVID-19.

“The discoveries by the two Nobel Laureates were critical for developing effective mRNA vaccines against COVID-19 during the pandemic that began in early 2020,” the Nobel committee said.

“Through their groundbreaking findings, which have fundamentally changed our understanding of how mRNA interacts with our immune system, the laureates contributed to the unprecedented rate of vaccine development during one of the greatest threats to human health in modern times,” the committee added.