The funding announcement says that candidate interventions should be efficacious and/or widely used. What does that mean?

Efficacious programs and interventions are those for which data demonstrate a positive impact on the outcome(s) of interest relative to a placebo within a specific population. The efficacy of interventions should be clearly described and cited in the research application using systematic reviews, prior empirical investigations, or other scientific documentation in the proposed population. If investigators claim that an intervention is widely used, they should provide a clear and thoughtful rationale for that claim accompanied by evidence of widespread use.