About Colds: Causes
Common colds are infectious, and can be passed from one person to another very easily. The average adult gets about one to three colds per year, most often during the winter. Infants can get up to eight in a year because their body's defences aren't yet developed.
Sneezing or coughing can easily transmit cold virus in droplets from an infected person's mouth or nose. Hand-to-hand contact is another way the virus is passed around. Since cold viruses can live for several hours on hard surfaces, you can even get infected by picking up an object recently touched by a person with a cold. It then takes hold by being rubbed into the eyes or nose.
A few myths about colds should be debunked - kissing doesn't usually spread the virus from one person to another, and neither does cold weather make you more prone to catching a cold. However, constantly moving in and out from warm places to the cold outdoors can cause a runny nose, making it easier for a cold virus to take hold.