In 1940 and 1941 we had the opportunity to study certain aspects of the attack rate of measles which we believe to be of value in the study of the epidemiology of this disease. That not all supposedly susceptible children will have measles after a particular exposure has been known for many years. Stocks1 has estimated that for every clinical case of measles in a densely populated area there are three times that number of children who become temporarily immune because of latent infection. It is reported, however, that in urban communities 90 to 95 per cent of persons will have contracted this disease by the time they attain adult life.2 The purpose of this paper is to record the attack rate and incubation period of measles in the 1940-1941 epidemic in New York city and to analyze certain sginificant factors that may affect the results.
The effect