Norovirus is one of those nasty winter bugs that just does not relent.

It can survive even the most potent of hand gels, as well as freezing temperatures, and it takes as few as 10 viral particles to make you sick.

So it’s no wonder really that so many people in the UK get struck down, and even end up hospitalised, with the illness each year.

The bug, which is characterised mainly by violent bouts of vomiting and diarrhoea, typically goes away in 48 hours. 

But those two days can seem like a lifetime when you’re firmly glued to the loo.

Why do some people get norovirus worse than others?

If you’re sat there smugly thinking you haven’t been bitten by the noro-bug this year, there might be a reason why. 

According to Professor Patricia Foster, an expert in biology at Indiana University Bloomington, your blood type as well as whether you make a certain antigen in your body, could influence your vulnerability to the winter illness.

She explained that people with the B blood type tend to be more resistant to the bug, while those with A, AB and O blood types are more likely to become ill. 

And here’s where things get a little complicated.

Prof Foster previously explained that a person’s blood type – whether A, B, AB or O – is “dictated by genes that determine which kinds of molecules, called oligosaccharides, are found on the surface of your red blood cells”.

These oligosaccharides are made up of sugars that are linked together. They attach to red blood cells – a bit like little koala bears – and can also be found in the cells that line your small intestine.

Now norovirus and some other viruses love these oligosaccharides because they can easily attach to them and then infect you via the intestine (cue: lovely gastro symptoms).

And a lot of norovirus strains need one oligosaccharide in particular, known as the H1-antigen, to hop on board. 

Now some people – about 20% of the European-derived population, Prof Foster suggested – don’t make the H1-antigen in their intestinal cells. And, as a result, they are less likely to get sick from norovirus. 

And for a similar reason, those with the B blood type tend to be more resistant because, as the BBC reported, fewer strains of norovirus have evolved to attach to their oligosaccharides.

Whew. The more you know...