Two scientists won the Nobel Prize in medicine for discoveries that enabled the development of mRNA vaccines against COVID-19.

The award was given to Katalin Kariko, a professor at Sagan's University in Hungary and an adjunct professor at the University of Pennsylvania, and Drew Weissman, who performed his prize-winning research together with Kariko at the University of Pennsylvania.

"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 panel that awarded the prize said on Monday.

Thomas Perlmann, secretary of the Nobel Assembly, announced the prize and said both scientists were "overwhelmed" by news of the prize when he contacted them shortly before the announcement.

Gunilla Karlsson Hedestam, part of the panel that chose the winners, said of their work that "in terms of saving lives, especially in the early phase of the pandemic, it was very important".

The Nobel Prize in physiology or medicine was won last year by Swedish scientist Svante Paabo for discoveries in human evolution that unlocked secrets of Neanderthal DNA which provided key insights into our immune system, including our vulnerability to severe COVID-19.

The award was the second in the family. Paabo's father, Sune Bergstrom, won the Nobel Prize in medicine in 1982.

Nobel announcements continue with the physics prize on Tuesday, chemistry on Wednesday and literature on Thursday. The Nobel Peace Prize will be announced on Friday and the economics award on October 9.

The prizes carry a cash award of 11 million Swedish kronor ($A1.5 million). The money comes from a bequest left by the prize's creator, Swedish inventor Alfred Nobel, who died in 1896.

The laureates are invited to receive their awards at ceremonies on December 10, the anniversary of Nobel's death. The prestigious peace prize is handed out in Oslo, according to his wishes, while the other award ceremony is held in Stockholm.