What should I do to dodge catching a cold on a plane?

QTHE last time I flew on a commercial airline, I returned with a cold — I’d tried Vicks First Defence Nasal Spray, as I understand the infection is caused by the air being recycled on the plane.

As I have chronic obstructive pulmonary disease (COPD), could you recommend anything that might stop me getting colds? E. L. Webb, Letchworth, Herts. IT’S an interesting question, but let me first point out that it’s not the aircraft or recycled air that’s the problem — it’s the close confinement with a lot of people. Indeed, I suspect that merely being in an airport, where multitudes of people from all over are closely gathered together, is an equal contributor — as is travelling by Tube in London during rush hour, with passengers packed like sardines.

It’s also why cases of the common cold peak around Christmas, at a time when so many of us congregate inside together.

When I was a practising GP, I got a cold so rarely I could never remember when I’d had my last one. Even now, I probably have one only every two or three years. When I do, the acute phase (where I feel under the weather, with a cough and sore throat) may last five to seven days, but the sequel of runny nose, congested sinuses and a cough will last only a week or so; for most, this can last longer, particularly if it descends on to the chest.

From which I think we can read that my immune response is very strong. I have a sense that my apparent immunity to colds comes from years of frequent exposure to the viruses that cause them. This theory is, I think, underlined by the fact that I do not recall my father, a hospital doctor, ever having a cold until after he retired. Within a few years of doing so, he seemed constantly to be ill with colds and, once in his 70s, he had endless infections.

That will partly have been because our immunity declines as we age.

But he was also heavily exposed, as my siblings and I constantly visited with children who imported respiratory viruses to which he would succumb.

Obviously, it’s not advisable for someone with chronic obstructive pulmonary disease (COPD) to try to acquire immunity to colds by seeking exposure to them.

COPD is the umbrella term for a variety of illnesses that stem from some degree of lung damage and inflammation in the airways. A cold can be a real problem, as it can lead to chest infection and deterioration in the ability to breathe freely.

So what should someone in your position do? More than 100 viruses can cause sore throats or colds. Minimising exposure to these is important for you so, if possible, avoid public transport and caution others to steer clear when they are unwell with a respiratory infection.

As to other measures, over the decades of my career, I have heard of many strategies thought to be effective — there was a vogue for high doses of vitamin C, but little evidence this reduced the frequency of respiratory infections.

I once heard that dentists would suck on lozenges containing zinc to protect themselves from viruses exhaled by patients, although this hasn’t stood up to scrutiny, either. Apart from inhaling potentially infecting viruses that are in the air exhaled by those who are infected or incubating, viruses may be transferred via your eyes, nose or mouth from your hands.

That’s why I’m a stickler for hand washing with soap and water after touching door handles, rails or any surfaces others have used — before allowing hands to go near the face. Antiseptic gels are no substitute.

Obsessive, yes, but it is a protection and something to remember after using keyboards, screens or any surface touched by others who may be less particular.

Not convinced? In a recent study, four card players had an invisible tracer introduced into their noses; they then played bridge.

At the end of the game, every one of the playing cards was identified as being contaminated with nasal secretions. You have been warned.