part of part of part_of infectious disease control strategy control strategy reactive endpoint fraction A rule that is part of an infectious disease control strategy specification and specifies at which fraction of a population a control strategy is to be discontinued. controlStrategyReactiveEndpointFraction A fraction of a population that is targeted for treatment at which the control strategy is discontinued. The concept derives from the epidemiological notion of ‘herd immunity,’ which is a level of immunity in a population at which there are not enough susceptible individuals for a contagious disease to maintain the chain reaction. Technically, it is when the effective reproduction rate <= 1, which means that infectious individuals at most infect one person during the course of their illness. rule