What is the recommended timeframe for implementing chemoprophylaxis after exposure?

• A. Within 24–72 hours, as soon as possible after exposure
• B. As soon as possible after exposure, ideally within 24–72 hours
• C. At least one week after exposure
• D. Not indicated for any exposure

Answer: (B)

Timing is everything with post-exposure chemoprophylaxis. The goal is to start treatment as soon as possible after exposure to prevent the pathogen from establishing itself. The most protective window is within 24–72 hours after exposure, because drug levels reach protective concentrations quickly and can interrupt the early stages of infection. Delaying beyond this window tends to reduce effectiveness and increases the chance that disease will develop. Starting much later, such as after a week, is not considered reliable for prevention. So the best phrasing is to begin as soon as possible after exposure, ideally within 24–72 hours.