This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'Measure of communicability of a disease \nSelect and explain. \nA. Case fatality rate, B. Secondary attack rate, C. Sullivan index, D. Incubation period', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Secondary attack rate : SAR is defined as “the number of exposed persons developing the disease within the range of incubation period, following exposure to primary case. SAR = No of exposed persons developing disease within the range of the incubation period ——(Total number of exposed/susceptible contact) x 100\nThe important features of SAR are:-\n\nThe primary case is excluded from both the numerator and denominator.\nDenominator is restricted to susceptible contacts of primary case.\nIn denominator, person should be susceptible → Immune person (to disease) are not susceptible to develop the disease, So they are excluded.\nDisease should develop within the range of incubation period.\n\nSAR is an important measure of communicability. Higher secondary attack rate means, more numbers of susceptible contacts are developing the disease after exposure to primary case.\nSo, higher the SAR higher is the communicability (infectiousness) of disease.', 'role': 'assistant'}]