Sir Elton John cut his New Zealand concert short this weekend after losing his voice – the tearful 72-year-old told fans he’d been diagnosed with walking pneumonia just hours before the gig.

But what is walking pneumonia? And how can you tell you have it?

The term is an informal name given to a less severe form of pneumonia that doesn’t usually require bed rest or hospitalisation – hence the ‘walking’ part.

Professor James Chalmers, GSK/British Lung Foundation chair in Respiratory Research at the University of Dundee, tells HuffPost UK: “Walking pneumonia is not a term we use in the UK but it is often used in the US or Australia. Here we would probably call it ‘mild pneumonia.’”

It can be caused by a bacteria or virus, and symptoms are usually more mild than full-blown pneumonia. However, you’re still likely experience a cough, fever, chest pain, mild chills and headache. So it’s probably not wise to try and work through it. 

“Many people develop coughs and colds at this time of year but this is not the same as ‘walking pneumonia’ – it is only pneumonia when the infection spreads to the lungs,” says Prof Chalmers. “It is important to note that pneumonia is diagnosed by an x-ray.”

If you have mild pneumonia, though, you may not need to have a chest X-ray. A GP may be able to diagnose it by asking about your symptoms and examining your chest, states the NHS. 

Mild pneumonia can usually be treated at home. The typical route of treatment involves plenty of rest and antibiotics – you should take the full course, even if they start to feel better – as well as drinking plenty of water.

Although most cases of pneumonia are bacterial and are not passed on from one person to another, ensuring good standards of hygiene will prevent germs spreading.

If symptoms don’t improve after three days of starting antibiotics, go back to your doctor. But it’s worth noting that you might keep coughing for up to a month after you’ve had walking pneumonia, possibly even longer.