How do you calculate the secondary attack rate of disease in epidemiology? - Answers

Number of new cases among contacts of known cases x multiplier--------------------------------------------------------------------------------------Size of the the contact population at riskThe secondary attack rate is the probability that infection will occur among people at risk given a reasonable incubation period following proven contact with infection persons (AKA known cases) or infected sourcesThe multiplier is usually a multiple of 100, often 1000, 100 000 or 1 000 000 depending on the population size.