Scientists don’t yet know why we have more colds in winter than in summer, but they’re working on it. One recent theory is that our noses are colder at this time of year, and each time we breathe in, the lining of our noses cools, reducing the effectiveness of our defence system in that area. And that makes us more prone to infection.
You’re also more likely to catch a cold if you’ve just been through a major event such as marriage, a death in the family or losing your job. Happy, calm people are less likely to be unwell than those who are anxious, angry or depressed.
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Colds are caused by viruses
There are more than 200 of them in total.The main culprits are rhinoviruses, which are responsible for 30-50 percent of colds in adults. The good news is that we catch fewer colds as we get older because our immune system has learned how to fight off the ones we’ve had before.
How your immune system causes cold symptoms
Interestingly, that’s what is responsible for making you feel really unwell. It responds to the virus by releasing substances called inflammatory mediators, including histamine, interleukins and prostaglandins, and they are what cause the actual symptoms.
- your blood vessels dilate (making your nose bunged up) and leak fluid
- mucus gland secretion increases, which is why your nose runs
- your sneeze and cough reflexes are triggered
- pain nerve fibres are sparked off, making you feel aching and weak.
"When the virus infects cells, it sets off a chain reaction," explains Professor John Oxford, virologist at St Bartholomew's and the Royal London Hospital and chair of the UK Hygiene Council. "You get a sore throat because the virus is replicating in the cells in the throat. Immune cells are attracted to the area to fight off the virus, causing slight swelling, and that’s when you get a sore throat. We’re at the edge of learning here, and there’s a lot of new knowledge coming out."
It seems we don’t all react in the same way to the same virus. "We do quite a lot of work where we get volunteers together in a hotel and infect them with the same virus, and we get a terrific variety of symptoms," explains Professor Oxford. "We don’t know why this is. It could be related to genetics - it’s something we’re working on. If we could find the answer to that it would be ace."
How to boost your immune system
How to avoid catching a cold
Coughs and sneezes really do spread diseases, but recent research from the University of Virginia found that the cold virus can survive on surfaces for 48 hours. So you can touch the TV remote control/fridge handle/door knobs up to two days after your sneezing other half last did so, and pick up the virus on your finger tips.
Catching a cold from your loved ones isn’t inevitable, although home is one of the most common places to pick up the virus. "You can take some preventive action by using what’s called social distancing," says Professor Oxford. "It means if your partner has a respiratory infection, just keep maybe six feet away, so if they do cough you probably won’t be infected so easily. Sleep in another room, don’t sit with your arm around them, just keep your distance.
"You should also increase your hygiene levels," he suggests. "A lot of these infections are transferred by touch. If you cough on a cup, someone else touches it and then touches their mouth, they could be infected. Make sure all your cups, plates and cutlery are washed at a high temperature, and be sure to wash your hands well and you can start breaking the chain of transmission. There’s also some evidence that things like First Defence can help." Wiping all those communal surfaces – the TV remote, telephones and handles – is worthwhile too.
How to avoid a cold
How to make your cold better
Short of living like a hermit through the cold season, the chances are that you’ll pick up at least one cold. So do you hot-foot it down to the chemist, make your own remedies, or tough it out? Professor Oxford votes firmly in favour of making yourself feel better. "I’m not sure if there’s any truth in the old wives’ tales, like feed a cold, starve a fever. When those observations were first made, there wasn’t very much you could do about anything. Now there is."
Nor is he convinced that it’s advisable to try and 'sweat it out'. "We know that bacteria don’t replicate in high temperatures, but I think the feeling at the moment is that we keep the afflicted person happy and comfortable. Take something quite simple, like paracetamol and it will bring your temperature down and you’ll feel more comfortable.
"There’s nothing wrong with an aspirin and a hot toddy. My suggestion would be honey, to soothe your throat, lemon, hot water and a dash of whisky if you like, and perhaps an aspirin or paracetamol."
The big question, though, is whether anything will make your cold shorter. "There isn’t anything at the moment," says Professor Oxford. "But there are some new drugs coming along. I would be surprised if there’s not something pretty effective in the form of a tablet for instance, in the next four years." There’s something to raise a glass of hot toddy to.
Cough cures – what works?
Ask Dr Mark Porter – how to avoid catching a cold on a plane
Do you have any advice for avoiding catching coughs and colds on planes? We are taking our family skiing to celebrate our 30th wedding anniversary and the last few times we have flown in winter we have both picked up a bug. It is an important trip and we want to be on top form. Might supplements help?
Some patients of mine swear by supplements such as high-dose vitamin C and echinacea, or zinc nasal spray (Vicks First Defence, for example), but the evidence isn’t that convincing, and I remain sceptical that any of these will provide useful protection when sitting next to someone on a plane who is coughing and sneezing.
The risks of picking up a virus (or a bacterium) on planes have been studied by a number of researchers over the years, but it’s a subject that is shrouded in urban myth. Modern aircraft do recirculate a lot of the air in the cabin – rather than take in fresh – but it passes through very efficient HEPA filters that manufacturers claim remove at least 95% of airborne microbes. And, contrary to what you may have heard, pilots don’t routinely shut down fresh-air intake to save fuel; indeed in many planes they can’t adjust it at all.
There isn’t much you can do about breathing the same air as hundreds of other passengers, but watch where you sit and what you touch: bugs can lurk on all sorts of surfaces too. Research by an American microbiologist, who took swabs on more than 20 planes, suggests window seats are less hazardous from a viral point of view than aisle ones. And try to avoid going to the loo, or riffling through the magazines in the pockets in front of you, as he found both were heavily contaminated with bacteria and viruses.
Other research suggests that the biggest risk comes from people in your row. If one of them has a cough or cold, you are far more likely to catch it than if they are sitting in front or behind. So book your family into the same row(s) when you check in.
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