Jut wondered if you have a link to any research on what works best after trauma to prevent PTSD. I would be interested to read more.
Have a read of:
http://www.info-trauma.org/flash/media-e/mitchellCriticalIncidentStressDebriefing.pdf and take note of the stages in CISD... being more focused at the responders versus survivors, however; CISD also happens at the survivor level.
You can read about critical incident stress management (CISM), which is something similar except that it focuses on discussing the traumatic events, and you will note a lot of follow-up issues that specifically cite more harm than good typically comes from this type of after incident intervention. The wikipedia references good source documents for a cross-examination of it.
This one is the piece of resistance... WHO actually have quite a good name for this method, being Psychological First Aid (PFA) and you can read about it directly from their document:
http://whqlibdoc.who.int/publications/2011/9789241548205_eng.pdf
You will notice on the introduction how it explicitly outlines that people at the local level, not mental health based, but actual people involved with the trauma, then run groups, discussions, events to help build the group of survivors / those affected so they can talk, communicate, grieve and heal together. The document cites the evidence of this type of approach versus professional psychological intervention.
You can Google any of the above names to find more. CISD is focused at the emergency services, CISM is a failed experiment counter to WHO recommendations, and PFA has been in practice after 9/11 and slowly developing to become what the WHO has now endorsed, documented and released above.
This approach has the best success for healing. For the then minority who it doesn't work for, that is when that minority need professional support. Treatment should always be tailored to help the majority, then specific further follow-up and treatment approaches are tailored to treat the minorities.
To put it absolutely as simple as I could for all readers, Post Traumatic Stress is a majority, and CSID & PFA are designed to treat it and provide a majority healing. The minority who continue to struggle, or who develop PTSD, then shift off to specialist treatment (psychological intervention), and those minorities within the minority (alcohol abuse, dissociation, drug abuse, et cetera) then have tailored treatment programs to deal with their outcomes specifically.