Pandemic severity index

The PSI was developed by the Centers for Disease Control and Prevention (CDC) as a new 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. Although designed for domestic implementation, the HHS has not ruled out sharing the index and guidelines with interested international parties. The index and guidelines were developed by applying principles of epidemiology to data from the history of the last three major flu pandemics and seasonal flu transmission, mathematical models, and input from experts and citizen focus groups. practices were combined in a more structured manner: ==Context==

During the onset of a growing pandemic, local communities cannot rely upon widespread availability of antiviral drugs and vaccines (See Influenza research). The goal of the index is to provide guidance as to what measures various organizations can enact that will slow down the progression of a pandemic, easing the burden of stress upon community resources while definite solutions, like drugs and vaccines, can be brought to bear on the situation. The CDC expects adoption of the PSI will allow early co-ordinated use of community mitigation measures to affect pandemic progression. ==Guidelines==

The index focuses less on how likely a disease will spread worldwide – that is, become a pandemic – and more upon how severe the epidemic actually is. The main criterion used to measure pandemic severity will be case-fatality rate (CFR), the percentage of deaths out of the total reported cases of the disease.The actual implementation of PSI alerts was expected to occur after the World Health Organization (WHO) announces phase 6 influenza transmission (human to human) in the United States. This would probably result in immediate announcement of a PSI level 3–4 situation. The analogy of "category" levels were introduced to provide an understandable connection to hurricane classification schemes, with specific reference to the aftermath of Hurricane Katrina. Like the Saffir–Simpson Hurricane Scale, the PSI ranges from 1 to 5, with Category 1 pandemics being most mild (equivalent to seasonal flu) and level 5 being reserved for the most severe "worst-case" scenario pandemics (such as the 1918 Spanish flu). The report recommends four primary social distancing measures for slowing down a pandemic: • Isolation and treatment of people who have suspected or confirmed cases of pandemic influenza • Voluntary home quarantine of household contacts of those with suspected or confirmed pandemic influenza • Dismissing school classes and closing daycare centers • Changing work schedules and canceling large public gatherings These actions, when implemented, can have an overall effect of reducing the number of new cases of the disease; but they can carry potentially adverse consequences in terms of community and social disruption. The measures should have the most noticeable impact if implemented uniformly by organizations and governments across the US. ==Response==

While unveiling the PSI, Dr. Martin Cetron, Director for the Division of Global Migration and Quarantine at the CDC, reported that early feedback to the idea of a pandemic classification scale has been "uniformly positive". which uses quadrants based on transmissibility and clinical severity rather than a linear scale. ==See also==