Peak age of occurrence is the second 6 months of life. Incidence does not fall significantly until the second decade of life. The number of colds increases during group child-care exposure in infancy. Exposure to viruses in schools and child-care centers serves to introduce viruses into the family. Boys have symptomatic respiratory tract illnesses more frequently than do girls. Usually, adults are victims rather than sources of common cold viruses; primary caregivers and infants have the highest rates of secondary illness.

Viruses causing the common cold spread from person to person by means of virus-contaminated respiratory secretions. Studies in adult volunteers suggested that rhinoviruses are spread by small airborne particles, by inhalation or impalement of large particles when transmitters and recipients are at very close range, and through self-inoculation after direct hand contact with a transmitter’s infected nasal secretions or indirect contact with contaminated objects. Direct contact is the primary means for the spread of the common cold. Compared with adults, infected children have higher concentrations of virus in secretions and longer duration of shedding. Coughing, talking, drooling, and kissing are not highly contagious behaviors. Sneezing, nose blowing and wiping, and hand transfer of secretions from paper tissues or environmental surfaces to nose or conjunctiva are more contagious behaviors.