The Queen had to pull out of attending the Royal Variety Performance last week – one of a number of engagements she's now missed through a chest infection.
At a recent event at Buckingham Palace, the Queen revealed to actress Emily Mortimer that she had stopped smoking 20 years ago.
This begs the question: could a history of smoking make those who have kicked the habit more susceptible to chest infections – and, if so, what can they do to protect themselves?
Ex-smokers are more prone to all sorts of infections, from colds and flu to pneumonia, experts say. They're also more likely to suffer from worse symptoms. 'Even if your lungs are left slightly damaged from smoking, you're more susceptible to getting infections,' says Professor Nick Hopkinson, a consultant respiratory physician at Royal Brompton Hospital in London and medical director of the charity Asthma + Lung UK.
In healthy lungs, sticky mucus (sputum) traps harmful particles and bacteria, moving them along to the throat to be swallowed and destroyed. Immune cells patrol the lungs at the same time, destroying any bugs. But in smokers, the lungs become inflamed and produce too much mucus. When this gets trapped, smokers cough it up.
It also causes direct lung cell damage, which makes it more difficult to inflate and deflate the lungs, leading to breathlessness.
'Once you start getting symptoms caused by smoking – including bringing up sputum, coughing and breathlessness – then it's more likely there's already some lung damage,' adds Professor Hopkinson.
Smoking also changes the microbiome (the community of bacteria and viruses) in the lungs.
This makes it easier for harmful bugs (particularly streptococci – a major cause of chest infections, particularly pneumonia) to cause further damage, explains William Cookson, a professor of genomic medicine at the National Heart and Lung Institute at Imperial College London.
If you continue to smoke, inflammation causes progressive scarring in the airways. Smoking for ten years or more is likely to cause permanent damage – which seems to make people prone to chest infections as well as raising the risk of disease, such as lung cancer, says Professor Cookson.
If you stop smoking, the inflammation on the lungs dies down, the immune system starts working better, the microbiome returns to normal and, while the scarring remains, it doesn't get worse.
'However, the scarring can make you vulnerable to chronic infections with harmful bugs, including Haemophilus influenzae and Streptococcus pneumoniae, which cause new damage and episodes of pneumonia – but ex-smokers don't suffer nearly as badly as continued smokers,' says Professor Cookson.
There are ways for current and former smokers to help keep chest problems at bay. 'Staying active is really important – exercise helps to improve lung capacity,' explains Dr John Conibear, clinical director for lung oncology at Barts Health NHS Trust in London. 'Even taking up singing will help improve it.'
Eating a healthy diet rich in antioxidants (berries, spinach and nuts) and omega-3 fatty acids (oily fish and flaxseed) can boost lung health, adds Dr Conibear, who's at the Harley Street Clinic in London, too. Try to avoid lung irritants, such as fumes from chemicals found in cleaning products, as they might cause further damage.
And note that it's never too late to quit. Smoking 'increases the risk of cancer, stroke, heart attack, cataracts, macular degeneration, erectile dysfunction and osteoporosis', says Professor Hopkinson.
'The gains from giving up can make a big impact, even if you quit when you're elderly – it's the difference between being able to walk to the car or not, or being able to play with your grandchildren.'
