This systematic review of 19 studies found that post-primary school-based suicide prevention initiatives targeting suicidal thoughts and behaviors were effective at reducing both suicidal ideation and attempts, especially if longer than a week, involving multiple stakeholders and with 12-month follow-up.

Walsh, E. H., McMahon, J., & Herring, M. P. (2022). Research Review: The effect of school‐based suicide prevention on suicidal ideation and suicide attempts and the role of intervention and contextual factors among adolescents: a meta‐analysis and meta‐regression. Journal of child psychology and psychiatry.

https://acamh.onlinelibrary.wiley.com/doi/full/10.1111/jcpp.13598?campaign=woletoc