Two scientists whose work led to the mRNA vaccines against covid-19 have been awarded the 2023 Nobel prize in physiology or medicine.
The technology was licensed by US biotech firm Moderna as well as German biotech firm BioNTech – where Karikó went to work – which then collaborated with the multinational Pfizer. This led to two of the main covid-19 vaccines used in high-income countries, from Moderna and Pfizer/BioNTech.
mRNA is a “messenger” molecule that allows genetic information stored in DNA, in the cell nucleus, to be transported to protein-making factories called ribosomes elsewhere in the cell.
There had long been interest in using mRNA medically to instruct human cells to manufacture proteins that they would not normally make. But if artificially synthesised mRNA is injected into the body, it looks similar to mRNA produced by bacteria – and so is destroyed by various immune chemicals.
While at the University of Pennsylvania in the 1990s, Karikó and Weissman worked out a way to chemically tweak synthesised mRNA so that it looks like the version naturally made by mammalian cells – and so avoid the immune attack.
In the covid-19 vaccine, the mRNA contains instructions for making the coronavirus spike protein, a molecule on the outside of virus particles. When someone is given the vaccine, their cells start to make this protein, which triggers a normal immune response.
The Moderna and Pfizer/BioNTech vaccines were widely rolled out in high-income countries from early 2021 onwards. Initially they were highly successful at stopping people from being infected with covid-19.
They are less successful at preventing infections with the omicron variants of the virus, which began spreading in late 2021. However, the vaccines are still effective at reducing illness severity and preventing deaths.
Many countries in the northern hemisphere have recently restarted covid-19 booster campaigns before an expected winter surge of the virus – although it is debated whether they should now be offered to most people or only those who are more vulnerable.
The mRNA covid-19 vaccines helped prevent countless deaths and severe ill health from the coronavirus and enabled societies to open up again, said Thomas Perlmann, the secretary of the Nobel Committee for Physiology or Medicine, at an announcement on 2 October. “The work had a major impact on society during the recent pandemic.”
Another advantage of mRNA technology is that it allows vaccines to be made more quickly against any new viruses – such as a bird flu pandemic, said Perlmann. “Future vaccines based on mRNA have the potential to become scalable, fast and flexible.”
They are also being investigated as potential treatments for cancer.