The Common Cold Unit (CCU) or Common Cold Research Unit (CCRU) was a unit of the British Medical Research Council which undertook laboratory and epidemiological research on the common cold between 1946 and 1989. It was set up on the site of the Harvard Hospital, a former military hospital at Harnham Down near Salisbury in Wiltshire. Common colds account for a third of all acute respiratory infections and the economic costs are substantial in terms of sick leave.