The Pandemic Severity Index (PSI) is a pandemic influenza planning tool for use by states, communities, businesses 
and schools, as part of a drive to provide more specific community-level prevention measures which is developed by The Centers for Disease Control and Prevention (CDC).
The Pandemic Severity Index, or pandemic mitigation interventions that will be describe in the article herein are such as home isolation and quarantine, dismissal of students from school, and workplace/community in adult social distancing. It is recommended that the measures be initiated early before explosive growth of the epidemic and, in the case of severe pandemics, that they be maintained consistently during an epidemic wave in a community.
This is an interim planning guidance on the use of nonpharmaceutical interventions in mitigating an influenza pandemic. It should be used to enable better prediction of the impact of a pandemic while provide recommendations among local decision maker to the severity of future influenza pandemics. Find the mitigation slide article of What You Should Know about Pandemic Severity Index (PSI) in the pdf filetype (source: cdc.gov), or you may read well-explanations in here.
