What does an epidemic curve (epicurve) illustrate?

• A. Chart of vaccination rates.
• B. Map of geographic spread.
• C. Graph showing the number of new cases over time to reveal outbreak dynamics.
• D. Line of mortality rates.

Answer: (C)

An epidemic curve shows how many new cases occur over time. The x-axis tracks time and the y-axis shows the number of new cases, so the shape of the curve reveals how the outbreak unfolds—when it starts, when it peaks, and how long it lasts. This helps you infer outbreak dynamics, such as whether transmission is from a single point source or through ongoing person-to-person spread, and it can indicate the impact of interventions as the curve changes. Other charts focus on different information: vaccination rates track coverage, geographic maps show where cases are located, and mortality-rate lines track deaths rather than new infections.