Good luck with that...
It would be ideal if people did that, but enough won't stay home and stop infecting others no matter how much you worry and bitch about it. So the smart course of action to take is just STFU and accept reality.
BTW, don't believe the old wives tales. There is no effective way to prevent a cold if exposed to the virus... with the exception of immunity to that particular strain. No amount of "immune system boosters", exercise, or healthy eating will stop you from getting a cold or flu if exposed assuming all other things are equal. They may, however, lessen the severity and duration a little bit.
A couple of examples:
Echinacea
Echinacea is a dietary herbal supplement that some people use to treat their colds. Researchers, however, have found that while the herb may help treat your colds if taken in the early stages, it will not help prevent them.
One research study funded by the National Center for Complementary and Alternative Medicine, a part of the National Institutes of Health, found that echinacea is not affective at all in treating children aged 2 to 11.
Vitamin C
Many people are convinced that taking large quantities of vitamin C will prevent colds or relieve symptoms. To test this theory, several large-scale, controlled studies involving children and adults have been conducted. To date, no conclusive data has shown that large doses of vitamin C prevent colds. The vitamin may reduce the severity or duration of symptoms, but there is no clear evidence.
Taking vitamin C over long periods of time in large amounts may be harmful. Too much vitamin C can cause severe diarrhea, a particular danger for elderly people and small children.
The only real prevention methods:
There are several ways you can keep yourself from getting a cold or passing one on to others.
*Because cold germs on your hands can easily enter through your eyes and nose, keep your hands away from those areas of your body
*If possible, avoid being close to people who have colds
*If you have a cold, avoid being close to people
*If you sneeze or cough, cover your nose or mouth.
Handwashing
Handwashing with soap and water is the simplest and one of the most effective ways to keep from getting colds or giving them to others. During cold season, you should wash your hands often and teach your children to do the same. When water isn't available, CDC recommends using alcohol-based products made for washing hands.
Disinfecting
Rhinoviruses can live up to 3 hours on your skin. They also can survive up to 3 hours on objects such as telephones and stair railings. Cleaning environmental surfaces with a virus-killing disinfectant might help prevent spread of infection.
