Among this year’s recipients of the Lasker awards, announced Friday, were two scientists whose work was crucial in the development of COVID-19 vaccines. The prizes are among the most prestigious prizes in medicine, and scores of Lasker winners have gone on to receive the Nobel Prize.

Katalin Kariko, a senior vice president at BioNTech, and Dr. Drew Weissman, a professor in vaccine research at the University of Pennsylvania’s Perelman School of Medicine, shared this year’s Lasker-DeBakey Clinical Medical Research Award.

Congratulations to all the 2021 #LaskerAward winners! — Dieter Oesterhelt, Peter Hegemann, and @KarlDeisseroth;
Katalin Karikó (@kkariko) and Drew Weissman (@WeissmanLab); David Baltimore
Missed the announcement? You can still see the video at https://t.co/w9Pw3YwBTP#Lasker2021 pic.twitter.com/ufYNNSfR5d

— Lasker Foundation (@LaskerFDN) September 24, 2021

In retrospect, their 2005 breakthrough was apparent when Kariko and Weissman proudly published a surprising finding they had made about messenger RNA, also known as mRNA, which provides instructions to cells to make proteins. The scientists noticed that when they added mRNA to cells, the cells instantly destroyed it. But they could prevent that destruction by slightly modifying the mRNA. When they added the altered mRNA to cells, it could briefly prompt cells to make any protein they chose.

But at the time, most scientists were uninterested in the technology, which was to become a keystone of mRNA vaccines, because they thought there were better ways to immunise.

Congratulations @kkariko and Drew @WeissmanLab, 2021 #LaskerAward winners!—“for the discovery of a new therapeutic technology based on the modification of messenger RNA—enabling rapid development of highly effective Covid 19 vaccines” #RNAbiology #Lasker2021 #LaskerLaureate pic.twitter.com/L8dxC4Pw1p

— Lasker Foundation (@LaskerFDN) September 24, 2021

Their paper, published in Immunity in 2005 after multiple rejections by other journals, got little attention. The discovery seemed esoteric.

Weissman and Kariko wrote grants to continue their work. Their applications were rejected. Eventually, two biotech companies took notice of the work: Moderna, in the United States, and BioNTech, in Germany. The companies studied the use of mRNA vaccines for flu, cytomegalovirus and other illnesses, but none moved out of clinical trials for years.

Then the coronavirus emerged. The strikingly effective vaccines made by Moderna and Pfizer-BioNTech use the modification Kariko and Weissman discovered.

This article originally appeared in The New York Times.