The infectiousness of a disease within households

Abstract

The potential that an infective has for infecting a given susceptible from the same household is quantified as a random variable depending on the duration of the infectious period, the severity of the illness and the mobility of the infective. Procedures for making inference about both the mean value and the variance of this potential are proposed. In particular, the proposed analysis makes it possible to test whether infectives display significant differences in their infectiousness. The methods apply to diseases which are moderately infectious and their implementation requires data on the sizes of outbreaks in a collection of households. The procedures involve only simple computations which are easily done manually. Common cold data are used to illustrate the results.