Science of Pandemic Influenza

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Science of Pandemic Influenza

• Stephen C. Schoenbaum, MD, MPH
• Executive Vice President for Programs
• June 15, 2006
• www.cmwf.org

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Limitations of Our Knowledge

• Direct or inferential virologic knowledge only
  about 1889, 1918, 1957, 1968, 1977
• Direct virus isolation only for the latter 3
• Virus reconstruction for 1918
• Direct pandemic experience with only H1,2,3 N1,2
• i.e., 3/16 hemagglutinin types 2/9 neuraminidase
  types

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Avian Flu (H5N1)

• Emerging pandemic among birds
• A unique observation (I believe) hence difficult
  to estimate the probability of its being a
  prelude to a human pandemic
• Some, but few, instances of spread to humans
• Hopeful, but not an absolute protection
• Has occurred with other strains (e.g., H7)
• Possibly a few instances of spread between humans
• Again, a concern but this has occurred with
  other strains without causing a pandemic (e.g.,
  Hsw1N1 H1N1 at Fort Dix, NJ in 1976

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Policy-Relevant Information About Pandemics

• Pandemics occur irregularly over time
• It is likely there will be another some time
• Pandemics vary in size
• All are important but not all have the impact of
  1918
• Disproportionate effect on younger people than
  interpandemic epidemics
• Policies for control need to be population-wide
• Can/do cause societal disruption
• Need contingency plans for vital societal
  functions
• Usually associated with a second, even third,
  wave

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Policy Options for Preventing or Ameliorating
Pandemic Spread

• Global surveillance for novel strains
• Occurring
• Leading to control of influenza in flocks of
  birds
• Hard to know if this can have an impact on
  prevention or amelioration of pandemic spread

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Policy Options for Preventing or Ameliorating
Pandemic Spread

• Developing methods for crash production of
  vaccines once a pandemic has been detected
• Stockpiling prototype vaccines for each of the
  influenza A hemagglutinins
• Prior immunization with prototypes of the
  influenza A hemagglutinins
• Immediate production/use of vaccines to
  ameliorate second/third waves

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Policy Options for Preventing or Ameliorating
Pandemic Spread

• Stockpiling antivirals and using them with
  emergence of a new strain
• Increasing routine use of antivirals
• Research to develop new antivirals
• Increased/repeat pneumococcal vaccination at time
  of emergence of a new influenza A strain
• Statins - ?other novel/general methods of
  reducing the lethality of bacteremia or of viral
  infections

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Policy Options for Preventing or Ameliorating
Pandemic Spread

• Social Distancing
• 1968 school closures (Xmas vacation)
• 1918 Quarantine of Australia
• Bottom line could buy some time
• Ability to enhance ICU/treatment capacity
• Respirators how many are really needed?
• Cross-trained staff will they show up?
• Antibiotics can we deal with resistance?
• Bottom line guess could probably handle a
  1957-size pandemic

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