In a village of 100 children, 60% are immunized against measles. One child travelled and returned with measles and infected other 26 children. What is the secondary attack rate -

Ans. is 'a' i.e., 67% Total children = 100 o Immunized children = 60 o Primary case =1 o Total no. of susceptible contacts = 100 - (60+1) = 39 o No. of Susceptible developed disease = 26 26 SAR = _______________ x 100 = 67% 39