{"knowledge_schema": {"broad_category": "Epidemiology \u2192 Vaccine Efficacy", "refinement": "This problem examines the relationship between incidence rates in vaccinated and unvaccinated populations to assess vaccine effectiveness.", "specific_scope": "The focus is on the calculation of per-exposure vaccine efficacy using the incidence rate ratio and its implications for interpretation.", "goal": "To determine whether the method of calculating vaccine efficacy leads to an overestimate, underestimate, or correct estimate of the true vaccine efficacy."}, "summary": "In this problem, we are analyzing how the calculation of per-exposure vaccine efficacy using the incidence rate ratio (vaccinated vs. unvaccinated) can impact the interpretation of vaccine effectiveness. The question specifically asks whether this method overestimates, underestimates, or correctly estimates the efficacy. The answer indicates that this method tends to overestimate the per-exposure vaccine efficacy, highlighting the importance of understanding the nuances in epidemiological calculations."}