"An influenza pandemic is expected to occur about once every 30 years. Pandemics can cause a large portion of the population to become ill with widespread overload of the healthcare system and possible disruption of basic infrastructure services (such as delivery of food to grocery stores). […] This document forms the core of the Indiana State Department of Health Pandemic Influenza Plan. It is intended to provide a brief outline of the plan so that a reader can quickly obtain an overview. Details will be provided in annexes to this plan so that readers may quickly move to the parts of the plan that are of immediate concern. This provides a format in which each individual/unit/group/agency can work with an annex of manageable size while having access to the entire plan when needed."