Two scientists won the Nobel Prize in medicine for research that laid the groundwork for some of the best-selling medicines of all time: the messenger-RNA vaccines against COVID-19.

Katalin Kariko and Drew Weissman’s work helped pioneer the technology that enabled Moderna and the Pfizer-BioNTech partnership to swiftly develop shots. The vaccines have been given to hundreds of millions of people around the world, a key step towards easing the coronavirus pandemic.

Bloomberg