What is the definition of risk?

• A. The rate of hospital admissions.
• B. The probability that exposure to a hazard will lead to negative consequences.
• C. The proportion of population vaccinated.
• D. The average time to recovery.

Answer: (B)

Defining risk in public health: it is the probability that exposure to a hazard will lead to negative health consequences. In this sense, risk depends on both the potential harm (the hazard) and the chance of coming into contact with it (the exposure), and it focuses on the likelihood of an adverse outcome among those exposed. This makes it different from other epidemiologic ideas like a rate of hospital admissions (which measures how often events occur over time), the proportion vaccinated (which describes coverage or how many people have received a vaccine), or the average time to recovery (which is a duration). For example, the risk of illness from drinking contaminated water is the probability that a person who drinks the water will become sick; if 5 in 1,000 exposed people become ill, the risk is 0.5%.