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Background: Mass drug administration (MDA) based on two doses of ivermectin, one week apart, substantially reduces prevalence of both scabies and impetigo. The Regimens of Ivermectin for Scabies Elimination (RISE) trial assessed whether one-dose ivermectin-based MDA would be as effective., Methods: RISE was a cluster-randomised trial in Solomon Islands. We assigned 20 villages in a 1:1 ratio to one- or two-dose ivermectin-based MDA. We planned to test whether the impact of one dose on scabies prevalence at 12 and 24 months was non-inferior to two, at a 5% non-inferiority margin., Results: We deferred endpoint assessment to 21 months due to COVID-19. We enrolled 5239 participants in 20 villages at baseline and 3369 at 21 months from an estimated population of 5500. At baseline scabies prevalence was similar in the two arms (one-dose 17·2%; two-dose 13·2%). At 21 months, there was no reduction in scabies prevalence (one-dose 18·7%; two-dose 13·4%), and the confidence interval around the difference included values substantially greater than 5%. There was however a reduction in prevalence among those who had been present at the baseline assessment (one-dose 15·9%; two-dose 10·8%). Additionally, we found a reduction in both scabies severity and impetigo prevalence in both arms, to a similar degree., Conclusions: There was no indication of an overall decline in scabies prevalence in either arm. The reduction in scabies prevalence in those present at baseline suggests that the unexpectedly high influx of people into the trial villages, likely related to the COVID-19 pandemic, may have compromised the effectiveness of the MDA. Despite the lack of effect there are important lessons to be learnt from this trial about conducting MDA for scabies in high prevalence settings., Trial Registration: Registered with Australian New Zealand Clinical Trials Registry ACTRN12618001086257., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Lake et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Scabies is a neglected tropical disease of the skin that can lead to impetigo, serious secondary bacterial infections and immune-mediated diseases. Mass drug administration (MDA) has been reported in several studies to reduce the prevalence of scabies and impetigo. We aimed to assess the efficacy of MDA for scabies on scabies and impetigo., Methods: We conducted a systematic review and meta-analysis of reports on the impact of MDA on scabies and impetigo. We included randomized control trials and observational evaluations reported from January 1970 to April 2021 and involving human participants. We searched PubMed, Ovid Medline, Embase, and Cochrane. We considered MDA as treatment intended for the whole population, regardless of individual infection status or symptoms. The main outcome assessed was the change in scabies and impetigo prevalence following MDA. This review is registered with PROSPERO (CRD42020169839)., Results: We identified 1110 records, of which 11 met inclusion criteria for the review and 9 were deemed suitable for meta-analysis for scabies and 4 for impetigo. Most studies were in small populations. There was a high degree of heterogeneity between studies (I2 value 96.19%). The overall relative reduction of the impact of MDA on scabies prevalence was 79%. The effect size was comparable for MDA based on ivermectin and permethrin. MDA for scabies also led to a reduction in impetigo prevalence with a relative reduction of 66%., Conclusions: MDA for scabies is highly effective in reducing the prevalence of scabies and impetigo. Further research is needed to determine the durability of impact, and the effectiveness of MDA regimens in larger populations., Competing Interests: Potential conflicts of interest. D. E. reports being Chair for International Alliance for the Control of Scabies, a not-for-profit association, unpaid role. M. H. reports payments to the institution outside of the submitted work from Bill and Melinda Gates Foundation, Coalition for Operational Research on Neglected Tropical Diseases, funded at The Task Force for Global Health primarily by the Bill and Melinda Gates Foundation, by UK aid from the British Government, and by the US Agency for International Development through its Neglected Tropical Diseases Program, and Australian Centre for the Control and Elimination of Neglected Tropical Diseases, National Health Medical Research Council Centre for Research Excellence; and Ackman Travelling Scholarship from the University of Melbourne paid to self. S. L. reports stipend paid to self for Postgraduate Health Research Scholarship—Royal Children’s Hospital Melbourne, Australia outside of the submitted work. A. C. S. reports being Co-Director of the Australian Strep A Vaccine Initiative, funding the Australian Government, Co-Direction of the Strep A Global Vaccine Consortium, funding by the Wellcome Trust, grants or contracts from the Australian Government Medical Research Fund, and Wellcome Trust outside of the submitted work; participation on a DSMB for studies on moxidectin for scabies—Medicine Development for Global Health (no payments); and President of the Lancefield Society (no payments). All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press for the Infectious Diseases Society of America.)