What is the main purpose of epidemiology?

• A. It's finding out the determinants (exposures) causing outcomes (death or disease) in a population.
• B. It is measuring only the prevalence of diseases in hospitals
• C. It is designing vaccines for infectious diseases
• D. It is studying pathogen genetics

Answer: (A)

Epidemiology aims to understand how different exposures or determinants influence health outcomes across a population and to map when and where diseases occur so we can prevent and control them. This means identifying risk factors, assessing how strongly an exposure is linked to an outcome, and observing patterns over time and place to guide public health actions. Measuring prevalence in hospitals is too narrow and misses the broader community picture, vaccine design belongs to developing interventions, and pathogen genetics focuses on the biology of the agent rather than the population-level patterns epidemiology seeks to explain.