“…The aim of risk communication during clusters/outbreaks is to alert PWUD to the ongoing event, to promote HR to reduce risk of exposure (for example, reduce heroin use or not to inject into the muscle or skin), promote symptom recognition and encourage timely healthcare seeking. There are no published studies that have examined the efficacy of such public health alerts for clusters/outbreaks of SFB and only a few studies have examined alerts in relation to other harms, such as alerts on heroin purity or drug adulteration following clusters of overdoses (Horyniak et al, 2010;Kerr, Small, Hyshka, Maher, & Shannon, 2013;Miller, 2007;Soukup-Baljak, Greer, Amlani, Sampson, & Buxton, 2015) or on changes in prescribed methadone dosages (Markwick, McNeil, Anderson, Small, & Kerr, 2016).…”