Question

A susceptible person develops disease within the range of the incubation period after coming in contact with a primary case. This is measured by:

• A. Secondary attack rate
• B. Case fatality rate
• C. Primary attack rate
• D. Tertiary attack rate

Hint:

Measures spread to contacts within one incubation period.

Answer 1

The Correct Option is A

Step 1: The scenario describes new (secondary) cases arising among contacts of an index case within the incubation period of the disease.

Step 2: The secondary attack rate (SAR) is defined as the number of exposed persons developing the disease within the range of the incubation period following exposure to a primary case, expressed as a proportion of susceptible contacts.

Step 3: It is a good measure of the infectivity or communicability of an agent and is often calculated within households.

Step 4: Case fatality rate measures deaths among cases and the primary attack rate refers to the index outbreak cases, so the correct answer is Secondary attack rate (option A).