Snuffles and sneezes are all too common, but if you're a smoker, you're more likely to suffer more from colds and flu than non-smokers. Smokers are more likely than non-smokers to die during flu epidemics. And children who are exposed to second-hand smoke have more severe responses when they get cold viruses.
But until now, it wasn't known exactly why this happens. Some scientists have suggested that cigarette smoke dampens down the immune responses to infection. New research from scientists at Yale School of Medicine in the US has finally answered the question - and found that the opposite is true..
Writing in the Journal of Clinical Investigation, the team showed that the immune systems of mice exposed to cigarette smoke from as little as two cigarettes a day for two weeks overreacted when they were also exposed to a mimic of the flu virus. The mice's immune systems did manage to get rid of the virus normally, but the exaggerated inflammation caused increased levels of tissue damage.
These findings suggest that smokers have problems not because they can't fight off the virus; but because they overreact to it. The lead author on the study, Professor Jack Elias, described it as" using the equivalent of a sledge hammer, rather than a fly swatter, to get rid of a fly."
The team also found that mice with viral infections that had been exposed to cigarette smoke developed emphysema faster, and had scarring in their airways.
Although the best way to avoid these problems is to quit smoking - or not to start in the first place, the team also uncovered the molecules that are involved in the exaggerated immune response in smokers. They hope that some of these might turn out to be good targets for future drugs to treat lung problems such as chronic obstructive pulmonary disorder, or to protect the lungs of smokers from damage.