<prompt> A ceain commuity has 100 children out of whom 28 are immunuzed against measles; 2 of them acquire measles simultaneously; Subsequently 14 get measles. Assuming the efficacy of vaccine to be 100. What is the sec. Attack rate -5102021.50  <response>: Ans. is c i.e., 20 o The impoant features of SAR : - i The primary case is excluded from both the numerator and denominator. ii Denominator is restricted to susceptible contacts of primary case. iii In denominator, person should be suscetible --- Immune person to disease are not susceptible to develop the disease, So they are excluded. iv Disease should develop within the range of incubation period. 