Pandemic Influenza: Assessing the Threat

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Pandemic Influenza Assessing the Threat
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Impact of SARS in Toronto

• In Ontario,
• provincial government costs have been estimated
  at 1.13 billion
• In Toronto,
• tourism industry lost 500 million
• 11 of businesses related to tourism reported
  layoffs (28,000 tourism jobs lost)
• Tourism has never recovered

Svoboda et al. NEJM, 2004
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1918
Oct 4th
Oct 5th
Oct 2nd
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In Toronto

• October 18th
• About 50 people a day are dying of influenza in
  Toronto
• Scouts and Guides help with distribution to the
  sick
• Cemeteries are ordered to stay open for Sunday
  burials
• Half the population sickened and 1,200 died

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The natural reservoir for avian influenza
H 16
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Defining the Disease

• Seasonal (Human) influenza
• Avian (Bird) influenza
• Pandemic influenza

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Seasonal (Human) influenza

• Ordinary influenza costs Canadian economy 1
  billion annually in direct medical costs and loss
  of productivity

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Avian (Bird) influenza

• A disease caused by influenza viruses carried and
  spread among birds

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Pandemic influenza

• A new strain of influenza virus that spreads
  quickly worldwide

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Pandemic influenza
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The 1918 Pandemic

• derived from an avian influenza virus
• An estimated one third of the world's population
  were clinically infected
• Case-fatality rates were gt2.5

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Taubenberger and Morens, EID, 2006
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What We Think We Know

• That there will be a pandemic

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What We Dont Know

• when it will occur
• which type of influenza will cause it
• how virulent
  or infectious it
  will be

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Is there reason to be concerned about H5N1?Or is
this just another Y2K?
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Unprecedented Spread in Poultry

• Previously highly pathogenic avian influenza was
  a rare disease in poultry
• Since 2003 H5N1
• loss of gt200 million poultry
• in gt50 countries effected in Asia, Europe and
  Africa

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Unprecedented Spread to Humans
Deaths
Total Cases
Country
99
172
Asia
5
8
Azerbaijan
5
13
Egypt
2
2
Iraq
4
12
Turkey
115
207
Total
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H5N1 is infecting a greater number of species
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Why havent we had an H5N1 pandemic by now?
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Genes that control host range
Avian
Human
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Attachment of H5N1 virus to respiratory tissues
of humans
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Assumptions

• That there will be three waves
• Each wave will last 6 to 8 weeks in a community
• That clinical disease attack rates will be 30
• Illness will be highest among school-age children
• Among working adults, an average of 20 will
  become ill during an outbreak
• That, depending on the severity, absenteeism may
  reach 40 during the peak weeks

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Severe Pandemic

• Initial panic
• Border disruptions
• Months of slowdown
• Economy will be hard hit
• Absenteeism's

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Worker Response in Pandemic

• Surveyed 308 public health workers in Maryland
• 46 said they would unlikely report to work
  during a pandemic
• 66 of employees felt they would be putting
  themselves at risk if they reported to work

John Hopkins and Ben Gurion University
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Supply risks

• Shortages already
• Reduction in labor
• Waste management
• Clean water
• Energy (electricity, fuel)

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What can we do to mitigate or prevent?
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Transmission of Influenza

• Airborne?
• Contact or large droplets?

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Measures to prevent or slow the spread on virus

• Reducing contact rates in the population
• Socially distancing
• Physical barriers
• Reducing infectiousness of infected individuals
• Treatment
• Reducing the susceptibility of uninfected persons
  
• Vaccination or antivirals

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Grappling with thorny issues
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N95 Masks
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N95 Masks

• Are they needed?
• Will you have to be fit-tested?
• How long can they be used for?
• Will there be enough of them?

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Antivirals for Prevention
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Antivirals for Prevention

• Which NI?
• Both Tamiflu and Relenza
• How long?
• 6 to 8 weeks
• How much?
• 1 capsule of tamiflu or 2 puffs once a day of
  relenza
• When do you start and when do you finish?

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Resources

• Flu Wiki
• CIDRAP (Center For Infectious Disease Research
  and Policy
• Ontario Ministry of Health and Long Term Care
  Influenza Pandemic
• Public Health Agency of Canada Canadian Pandemic
  Influenza Plan