Research conducted to promote prevention of illness in humans derives from all scientific disciplines, from the most basic molecular and cell biology to population sciences such as epidemiology. For example, studies of the most basic molecular cell biology and genetic mechanisms may be critical to developing a vaccine, understanding the genetic basis of disease susceptibility, or defining the adverse effects of a chemopreventive intervention. However, ultimately, all proposed preventive interventions must be evaluated in human populations, often starting with studies that define those at increased risk of the conditions of interest, proceeding to randomized, controlled intervention trials to evaluate the efficacy of the intervention. Where such trials are not feasible or ethically justifiable, epidemiological studies are needed to determine whether a net positive health benefit exists—and if so, for which populations.
ROBERT B. WALLACE