Intervention sustainability is a critical yet understudied aspect of implementation science research. To address this gap, we examined the sustainability of the Women's Health CoOp (WHC), a gender-focused, evidence-based, HIV and alcohol risk-reduction intervention, after an implementation trial. We used a mixed methods design consisting of questionnaires (n = 12), 3 focus groups (n = 11), and a semistructured interview conducted with interventionists implementing the WHC in clinics and substance use treatment programs in Cape Town, South Africa. Five out of 8 facilities implemented the WHC beyond the 6-month implementation period, and 4 were still implementing the WHC as of October 2019. Sustainability ranged from approximately 8 months to more than 3 years. At the most recent assessment, interventionists delivered the intervention to 0-20 participants in the past month. Qualitative findings indicate that long-term sustainability would require support from upper management, staff dedicated to the WHC, and booster trainings. The WHC was sustained postimplementation. Integrating the program into usual care would be feasible; however, human resources, financial, and institutional support would be needed for sustainability. To move implementation science forward, it is essential to determine sustainability beyond the presence and involvement of researchers.
