how single is “single” - some pragmatic reflections on single versus multifaceted interventions to facilitate implementation; comment on “translating evidence into healthcare policy and practice: single versus multifaceted implementation strategies – is there a simple answer to a complex question?”

an earlier overview of systematic reviews and a subsequent editorial on single-component versus multifaceted interventions to promote knowledge translation (kt) highlight complex issues in implementation science. in this supplemented commentary, further aspects are in focus; we propose examples from (kt) studies probing the issue of single interventions. a main point is that defining what is a single and what is a multifaceted intervention can be ambiguous, depending on how the intervention is conceived. further, we suggest additional perspectives in terms of strategies to facilitate implementation. more specifically, we argue for a need to depict not only what activities are done in implementation interventions, but to unpack functions in particular contexts, in order to support the progress of implementation science.