Professor Janet Lord

But if you're 70, 80 years old and you get the flu, there's a good chance you could end up in hospital and even die as a result because you get secondary infections like pneumonia as well.

So that's one thing.

That's one very visible thing that most of your viewers will know that the older you are, you're in a high risk category.

It is a marker of ageing.

So it's something we recognise, but it's not inevitable.

Yes, it's certainly one of the key drivers, we think.

Other things happen as well that can affect your immune system, but inflammation is looking like a major driver.

Another aspect that, again, your viewers will recognise and think about as an old person is walking more slowly, perhaps less struggling to get out of a chair, groaning every time you get out of the chair.

And that is because with age, our muscles, we have less muscle and it's less good quality muscles.

It's called sarcopenia.

So you lose muscle strength and we know that inflammation is one of the drivers there.

So this inflammation actually does lots of things to muscle.

It slows down the production of molecules that you need to grow the muscle.

They're called growth factors.

So it suppresses that.

It also causes the production in the muscle of hormones, stress hormones.

And again, some of your viewers may have heard of one called cortisol.

And cortisol breaks muscle down.

So it's suppressing the growth of new muscle and it's accelerating the breakdown of existing muscle.

So again, inflammation, we know, drives this cortisol production and suppresses these growth factors.