The common cold most often is transmitted by direct contact with germs from the nose, mouth, or coughed or sneezed droplets from someone who is infected, usually by hand-to-hand contact. Virus particles are passed from one person's hand to another person's hand. The second person then touches his or her eyes or rubs his or her nose, spreading the virus there, where the virus can start a new infection. It is possible to become infected by touching a surface, such as a tabletop or doorknob that was recently touched by an infected person, and then touching your eyes or nose. These viruses also can be spread by inhaling particles from the air after an infected person has coughed or sneezed.
Usually about half of the family members of an infected person will become ill. Colds also are transmitted frequently in schools and day care facilities.
To avoid getting or spreading a cold, it helps to clean your hands often, carefully dispose of all used tissues, and avoid rubbing your eyes and nose. If possible, you should avoid close, prolonged exposure to people who have colds.
People who exercise regularly, especially those who exercise daily, have fewer colds per year than those who are less active.