Healthcare Epidemiology

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Pandemic Influenza What we know What we dont
know
Lisa M Koonin, MN, MPH Division of Partnerships
and Strategic Alliances National Center for
Health Marketing/CCHIS Centers for Disease
Control and Prevention
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Introduction to Influenza

• Seasonal, avian, and pandemic
• Reducing transmission of influenza
• Planning for businesses

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Definition of Influenza

• A contagious disease caused by an RNA virus
• Primarily affects the respiratory tract
• Can cause severe illness and lead to
  life-threatening complications
• A global infectious disease threat
• An annual public health problem

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Flu Terms Defined

• Seasonal (or common) flu
• Can be transmitted person to person
• Most people have some immunity
• Vaccine is available
• Avian (or bird) flu
• Can be transmitted from birds to humans
• No human immunity
• No human vaccine is commercially available
• Pandemic flu
• Can spread easily from person to person
• Little or no natural immunity
• No vaccine available

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Average Seasonal Impact of Influenza in the
United States

• gt200,000 hospitalizations / year
• About 36,000 deaths / year
• Substantial economic impact
• Lost work / school days
• Estimated 37.5 billion cost

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• Influenza A Viruses

• Subtyped based on surface glycoproteins
• 16 hemagglutinins (HA) and 9 neuraminidases (NA)
• Current human subtypes H1N1, H3N2

HA
NA
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Avian Influenza A Viruses
Human Influenza A Viruses
H1 H16
H1 H3
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Pandemic Strain Emergence Reassortment of
Influenza A Viruses
Human virus
Avian virus
Avian Reservoir
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Pandemic Strain Emergence Direct Infection
Avian virus
Avian Reservoir
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Human Acquisition of Avian Influenza H5N1
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Three Criteria for a Pandemic

• A new influenza A virus appears or emerges
  
  in the human population, and
• It causes serious illness in humans, and
• It spreads easily from person to person
  worldwide
• Currently there is no human pandemic influenza in
  the world.

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Emergence of Influenza A Viruses in Humans
H9
1998 1999 2003
H5
1997 2003-2006
H7
1980 1996 2002
2003 2004
H1
H3
H2
H1
1977
1915 1925 1935
1945 1955
1965 1975 1985
1995 2005
2006
Avian Flu
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Influenza Virus Transmission

• Respiratory route
• Primarily by large droplets
• Through coughing or sneezing
• Possibly small particle short distance aerosols
• Contact
• Hand contact with secretions

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Potential Tools in Our Toolbox

• Vaccine will probably be unavailable during the
  first wave of a pandemic
• The supply of antiviral medications is limited
• Infection control and social distancing measures
• Transmission Interventions (Infection Control)
• Contact Interventions (Social Distancing)

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Infection Control Measures

• Transmission Interventions (Infection Control)
• Hand hygiene
• Facemasks
• Cough etiquette
• Sick people stay home (isolation)
• Stay home if have an ill household member
  (voluntary quarantine)
• Environmental cleaning

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Evidence for Benefits of Hand Hygiene

• Hand hygiene reduces the respiratory infections
  in healthcare and community settings.
• Among Navy recruits
• Am J Prev Med 20012179-83
• Handwashing program implemented at a Navy
  training center.
• 45 reduction in outpatient visits for
  respiratory illness.
• Frequent hand washers had fewer respiratory
  illnesses.

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Social Distancing Measures

• Contact Interventions (Social Distancing)
• School closure
• Keeping children and teens at home
• Cancellation of mass gatherings
• Alternatives to face-to-face contact at work
• Increasing distance between people
• Decreasing contacts

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Evidence for Benefits of Physical Separation

• Proximity of less than 3 feet has been associated
  with increased risk for transmission of
  infections via respiratory droplets.
• New Engl J Med 19823071255-7
• Am J Med 19484690

P0.0001 for the difference
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Social Space of Children at School
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HHS Pandemic Influenza Doctrine Saving Lives

• Quench outbreak at first site of cases
• Prevent or at least delay introduction into the
  United States
• May involve travel advisories, exit or entry
  screening
• For first cases, may involve isolation /
  short-term quarantine of arriving passengers
• Reduce transmission and spread of the disease

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The Pandemic Wave
1. Delay disease transmission and outbreak
peak 2. Decompress peak burden on
infrastructure 3. Diminish overall cases and
health impacts
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Pandemic Influenza Planning for Businesses
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Current WHO phase of pandemic alert
http//www.who.int/csr/disease/avian_influenza/pha
se/en/index.html
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Pandemic Influenza Checklist

• Provides framework for action
• Moves from uncertainty to measured, informed
  action
• Identifies key elements for planning

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Pandemic Influenza Planning for Businesses

• Plan for the impact on organizations and
  operations
• Plan to protect people
• Establish policies
• Allocate resources
• Communicate to and educate people
• Coordinate plans, response, and recovery

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Resources

• http//www.pandemicflu.gov/
• Business Checklist
• The Implementation Plan For The National Strategy
  For Pandemic Influenza
• Pandemic Influenza Planning Tools for Businesses
  (forthcoming)

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Complacency is the enemy of health protection!
www.pandemicflu.gov
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Containment May Be Possible
Without intervention, expect international
spread in 1 month and U.S. cases in 1 to 2 months.

• Failed containment may still delay international
  spread by 1 month
• Severe travel restrictions may delay U.S. cases
  by 1-4 weeks
• Border screening difficult because persons may
  transmit infection for up to a day before they
  develop illness