  Some interventions may include important spillover or dissemination effects
between study participants. For example, vaccines, cash transfers, and
education programs may exert a causal effect on participants beyond those to
whom individual treatment is assigned. In a recent paper, Buchanan et al.
provide a causal definition of the "individual effect" of an intervention in
networks of people who inject drugs. In this short note, we discuss the
interpretation of the individual effect when a spillover or dissemination
effect exists.
