At what stage of an epidemiologic investigation are control and prevention measures implemented?

• A. Intervene & evaluate
• B. Data collection
• C. Hypothesis generation
• D. Communication of results

Answer: (A)

Action to stop the outbreak happens in the intervention and evaluation stage. This is the phase where control and prevention measures are actually put into place—such as isolating cases, implementing vaccination or prophylaxis, ensuring safe water and sanitation, environmental controls, and communicating risk to the public—and then checked to see if they reduce new cases or transmission. Data collection and hypothesis generation are about gathering information and developing explanations first, while communication of results is about sharing findings after interpretation. The essence here is that taking and assessing concrete actions to reduce risk is the core activity of this stage.