Here are 10 high-yield MCQs on Secondary Attack Rate for NEET PG 2026, sourced directly from Park's Textbook of Preventive & Social Medicine and core epidemiology principles:

A) Number of new cases in a community per 1000 population B) Number of exposed persons developing disease within the incubation period per total exposed contacts C) Number of deaths per total number of cases in an epidemic D) Total cases in an outbreak divided by total population at risk

Explanation: SAR = (Number of exposed persons developing disease within the incubation period / Total number of exposed/susceptible contacts) × 100. The primary case is excluded from both numerator and denominator. - [Park's PSM, Secondary attack rate section]

A) 33.3% B) 50.0% C) 66.6% D) 40.0%

Explanation: Primary case excluded. Susceptible contacts remaining = 3 children. New cases = 2. SAR = 2/3 × 100 = 66.6%. Immune parents are excluded from denominator. - Park's PSM

A) Severity of disease B) Infectivity/communicability of an agent C) Case fatality in an outbreak D) Herd immunity threshold

Explanation: SAR is described as "an important measure of communicability." It reflects the ability of an infectious agent to spread from person to person in a susceptible population (e.g., in households/closed groups). - Park's PSM

A) It includes the primary case B) It includes only clinical cases C) It consists of all exposed susceptible contacts, excluding the primary case D) It includes all community members

Explanation: The denominator consists of all exposed contacts (or specifically susceptible contacts if identifiable). The primary (index) case is excluded from BOTH numerator AND denominator. - Park's PSM

A) Diseases with long communicable period (e.g., tuberculosis) B) Diseases where the primary case is infective for a short period (e.g., measles, chickenpox) C) Non-communicable chronic diseases D) Vector-borne diseases

Explanation: SAR is best applied when the primary case is infective for a short period (days), like measles and chickenpox. For diseases with long communicability like TB, the formula uses person-weeks/months/years of exposure in the denominator. - Park's PSM

A) 19.8% B) 25.0% C) 21.5% D) 17.0%

Explanation: SAR = 17 / (86 - 18) × 100 = 17/68 × 100 = 25.0%. The 18 primary cases are subtracted from the denominator as they are not susceptible contacts. - CDC Epidemiology Principles (Lesson 3)

A) Measuring person-to-person transmissibility B) Evaluating vaccine efficacy by comparing vaccinated vs. unvaccinated contacts C) Determining the source of a food-borne outbreak D) Studying spread within closed groups like households, barracks, dormitories

Explanation: SAR is used in closed/household settings to measure person-to-person spread and can compare attack rates in vaccinated vs. unvaccinated populations. Identifying the source of a food-borne outbreak relies on food-specific attack rates, not SAR.

A) It can measure the R0 value directly B) Vaccinees and non-vaccinees from several families can be pooled to determine overall attack rates in each group C) It adjusts for the latent period of a disease D) It measures herd immunity directly

Explanation: An additional advantage of SAR is that vaccinees and non-vaccinees from several families can be added to determine the overall attack rates in the vaccinated and unvaccinated populations, provided the same case and immunization definitions are used. - Park's PSM

A) Total family members B) Total susceptible contacts minus primary case C) Number of person-weeks (months or years) of exposure D) Total population of the community

Explanation: Since TB has a long communicable period, duration of exposure is an important factor. The denominator is expressed as person-weeks, person-months, or person-years of exposure, instead of a simple count of contacts. - Park's PSM

A) Measles B) Pertussis (Whooping cough) C) Chickenpox D) Mumps

Explanation: Without post-exposure prophylaxis, the SAR for pertussis is >80% among susceptible persons - making it one of the most contagious bacterial diseases. Treatment with azithromycin or clarithromycin reduces this spread. - Symptom to Diagnosis, 4th Ed.