Usually a rhinovirus. However, many other viruses can also cause the common cold. Children get repeated common colds as immunity to one virus does not give protection against other viruses. The viruses causing the common cold are infectious and can be passed from person to person by sneezing and coughing (droplet spread). The virus is then inhaled and infects the lining of the nasal passages. The virus can also be spread by hand to hand contact. One person coughs into their hand, and later hold hands with someone else who then rubs their nose. In this way the virus is spread from the nose of one person to another. The common cold is particularly frequent in young children who attend a crèche or play group, nursery school or school for the first time. Here children are exposed to viruses they have not met before. The patient is often infectious for a day or two before the signs and symptoms of a common cold appear.
As there are more than a hundred subtypes of rhinovirus, one child can repeatedly catch a common cold.