I’ve heard that if you wash your hands more often during the cold and flu season you may actually reduce the chances of getting sick. Is this true?
The short answer is yes: Hand washing almost certainly does help reduce the chances of catching colds, and may do so for flu as well.
The long answer is, it depends on the virus. There are several kinds of influenza virus. (If you have ever had a flu shot, you may have noticed that it contained components from both influenza A and B strains.) The influenza virus changes its coat — literally — so frequently that it is necessary to make up a new vaccine every year to cover the strains that are circulating during that year.
When a person has the flu, their coughing propels mucus and saliva containing the virus for a considerable distance. Others then inhale the virus particles to continue the infection. I don’t know whether the flu virus can survive for long on surfaces like tables and door knobs, as some of the cold viruses can. If they do survive, then hand washing would be helpful.
Hand washing will definitely reduce the transmission of colds, which are caused by many different viruses. The most common are probably the rhinoviruses, spread by droplets of mucus and saliva spread when we cough. These viruses are able to live for awhile on inanimate surfaces, so you are liable to pick them up on your hands and carry them to your nose, spreading the infection.
Because there are so many cold viruses, even people with healthy immune systems commonly have two to three colds per year. Several colds per year does not mean you are lacking in immunity, and there is no evidence that vitamins, (except possibly vitamin C) or special nutrition will improve the situation. If you are in contact with small children who pick up new viruses in school, you will probably experience your full quota. People with HIV — who may have very severe damage to their immune systems — do not appear to be more susceptible to colds than healthy people. In one study, volunteers exposed to very cold weather were found to have no more colds than people who stayed indoors.
So live a prudent life, eat well, exercise, don’t smoke, and wash your hands. Despite all of this, every once in awhile you’ll bump into a cold virus you haven’t met before — and it’ll get you.