The epidemiology of the common cold II. Cross-infection and immunity

Abstract

Analysis by epidemiological methods of the spread of the common cold among office workers and their families has failed to account for more than a fraction of the infections as a consequence of known exposure to infected individuals. Infections too mild to be recorded as colds, survival of the virus in the environment and its subsequent dispersal are considered as possible explanations of this.The distribution of serial intervals between colds suffered by members of the same family indicates that the median interval between the onset of an infection and the first symptom in infection apparently arising from it as cross-infections was between 21½ and 31½ days. This is only slightly longer than the median interval, 2·4 days, observed between nasal installation and the onset of symptoms in experimental infections.There is some epidemiological evidence that susceptibility to the common cold is reduced during the weeks following a cold.We should like to repeat, in this the second paper in this series, our thanks to the Ministry of Pensions and National Insurance and to the Shell Petroleum Company, to those members of their staffs and to the nurses and others who helped us in this investigation.