Briefing on Impact of a Global Epidemic

Institute Director Greg Evans presents briefing on Impact of a Global Epidemic to Air Force audience at Scott Air Force Base. November 1 presentation was part of the annual workshop for members of the Chemical, Biological, Radiological, Nuclear, and Explosives Response Unit

Given to:
USAF C-CBRNE Workshop
Scott Air Force Base
November 1, 2005

• Pandemic is a global outbreak of disease (global epidemic)
• Stages of a Pandemic
  • Interpandemic period
    • Phase 1: No new influenza virus subtypes have been detected in humans. An influenza virus subtype that has caused human infection may be present in animals. If present in animals, the risk of human infection or disease is considered to be low.
    • Phase 2: No new influenza virus subtypes have been detected in humans. However, a circulating animal influenza virus subtype poses a substantial risk of human disease
  • Pandemic alert period
    • Phase 3: Human infection with a new subtype, but no human-to-human spread, or at most rare instances of spread to close contact
    • Phase 4: Small cluster with limited human-to-human transmission but spread is highly localized, suggesting the virus is not well adapted to humans.
    • Phase 5: Larger clusters but human-to-human spread still localized, suggesting that the virus is becoming increasingly better adapted to humans but may not yet be fully transmissible (substantial pandemic risk)
  • Pandemic period
    • Phase 6: Pandemic: increased and sustained transmission in general population
• Consequences of a pandemic
  • In the absence of any control measures, it has been estimated that in the US a “medium-level” pandemic could cause 89,000 to 207,000 deaths, 314,000 to 734,000 hospitalizations, 18 to 42 million outpatient visits, and another 20 to 47 million people being sick.
  • Between 15% and 35% of the US population could be affected by an influenza pandemic
  • The economic impact could range between $71.3 and $166.5 billion.
  • Dramatically reduce number of health-care workers and first responders available to work
  • Hospital beds, equipment, and supplies will probably be inadequate
  • Might also impact blood donations
  • Social disruption
• Three 20th century avian influenza pandemics spread around the world within a year of being detected
  • 1968-69 Hong Kong flu [A (H3N2)] caused about 34,000 deaths in US
  • 1957-58 Asian flu [A (H2N2)] caused about 70,000 deaths in US
  • 1918-19 Spanish Flu [A (H1N1)] 500,000 died in US and 50 million worldwide
    • many died within first few day after infection and others of secondary complications
    • nearly half of those who died were young, health adults
    • US Military deaths from flu, 43,000 (out of 100,000 US troop casualties in WWI
    • High percentage of young developed pneumonia
    • 20-50% morbidity
    • Highly contagious
    • Successive waves
• Changes since 18th century
• Population increase from less than 1 billion or 6 billion
• Intercontinental travel in hours not months
• Millions traveling not hundreds
• Increase in human crowding
• Population health has improved
• Development of vaccines and antivirals
• Health care has improved
• Seasonal outbreaks or “epidemics” of influenza are caused by subtypes of influenza viruses that already circulate among people whereas pandemic outbreaks are caused by new subtypes that have never circulated among people or not for a long time
  • Seasonal epidemic result in over 200,000 hospitalizations a year and over 36,000 deaths
• Possible causes of pandemic
  • Antigenic shift - when a new influenza A subtype to which most people have little or no immune protection infects humans
  • Reassortment - human who is co-infected with avian influenza A virus and a human strain of influenza A virus
• Can circulates for many years
  · May include waves of influenza activity separated by months
• Avian flu designated as H5N1 in our most recent concern
  • H= hemagglutinin
  • N= neuraminidase
• Subtype differ based upon certain proteins on the surface of the virus (HA protein or NA protein)
• Virus can be high or low pathogenic
  • Highly pathogenic H5 can kill up to 100% of poultry
• 120 cases 60 deaths reported as of October 2005 in Asia and Europe
• No vaccine presently available
  • Ongoing trials of a vaccine made from an H5N1 virus isolated in Southeast Asia in 2004
  • Six to eight months to produce first lot of vaccine
• Available antivirals
  • Used primarily for treatment of diseased persons
  • Must be started as soon as possible and within 48 hours
  • Tamiflu 2.3 million doses in SNS Neuraminidase inhibitor
  • Zanamivir (Relenza) 83,000 doses
• Federal coordination and response (Draft Pandemic Influenza Preparedness and Response Plan)
  • Department of Homeland Security has primary responsibility for coordination of non-medical support
  • Health and Human Services will coordinate the overall public health and medical emergency response
  • President can declare an emergency activating the Federal Response Plan
• Most of response will be local because federal resources will be spread too thin
• Diseased cases must be isolated and treated
• Quarantine and personnel hygiene important for limiting spread before vaccines are available
• Very difficult to avoid introduction to US because infected people will appear well in early stages of disease
• Need for non-traditional sites to help address temporary surge needs
• Individuals in home quarantine or ill persons taken care of at home will require home health care, delivery of prescription drugs, and meals
• Vaccines will be important for stopping the epidemic
  • Will not be available for six to eight months after first cases
  • Need to target priority groups when vaccines become available
• Need effective communication with community to maintain public awareness and avoid social disruption
• Specific implications for the Air Force
  • Close living quarters for personnel
  • Incapacitation of up to 50% of pilots, mechanics, and other support personnel
  • Need for facilities for isolation and quarantine
  • Inadequate medical care facilities, equipment, supplies, and personnel
  • Need to determine priorities for receiving vaccines and antivirals
  • Might be required to provide logistical support to civilian populations
  • Increased difficulties if involved in a war