Vaccines against viruses like flu, Covid and RSV already exist and protect millions of people every year – but there has never been a vaccine licensed against norovirus, external.

The vaccine being trialled is made by Moderna and is an mRNA vaccine. Like the company’s Covid jab, it delivers instructions to our immune systems on how to recognise an invasive virus and protect against it by producing antibodies.

What’s tricky about norovirus is that it’s difficult to pin down.

“There is a broad and shifting diversity of genotypes over time”, says Dr Patrick Moore, a GP from Dorset, and chief investigator of the study.

So this vaccine contains three of the most common strains of the virus to get the best result possible.

There are still many unknowns – for example, how long will protection from it last, how effective will it be and how often will the vaccine need to be updated?

Answers to those questions should be answered during the trial, which is a collaboration between the UK Government, the National Institute for Health and Care Research (NIHR) and Moderna.

Twenty-seven NHS hospitals and centres in England, Scotland and Wales will take part in the trial, with half of those recruited given the vaccine, and their health compared to that of other volunteers.

Researchers will also be looking out for side-effects of the vaccine.

Several other drug companies are also developing and trialling norovirus vaccines, including HilleVax and Vaxart.