The effectiveness of rapid response vaccination in an outbreak is primarily measured by

• A. Increase in overall vaccination coverage across the population over time
• B. Reduction in transmission due to higher immunity levels
• C. Only the rate of adverse events after vaccination
• D. Number of vaccines wasted

Answer: (B)

Effectiveness in an outbreak hinges on reducing transmission by raising population immunity quickly. When vaccination is deployed rapidly, the goal is to lower the effective reproduction number so transmission chains break and new cases decline. This makes the primary measure the actual impact on transmission—seen as fewer new infections and a drop in incidence after the campaign—rather than just how many people were vaccinated. Safety metrics like adverse events and logistical issues like vaccine wastage matter, but they don’t by themselves show outbreak control. In polio, boosting intestinal and systemic immunity quickly is what interrupts spread, so the key indicator is the decrease in transmission and new cases following the rapid response.