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88 Years of Influenza 88 Years of Influenza Pandemics in 15 MinutesPandemics in 15 Minutes
Peter C. Kelly, M.D.Peter C. Kelly, M.D.Arizona Dept. of Health ServicesArizona Dept. of Health Services
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It’s all about the virusIt’s all about the virus
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Influenza VirusInfluenza Virus
RNA, 8 segmentsRNA, 8 segments Unstable,mutates Unstable,mutates
frequentlyfrequently Surface proteinsSurface proteins
• HemagglutininHemagglutinin• NeuraminidaseNeuraminidase
Niche in nature is Niche in nature is birdsbirds
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Drift and ShiftDrift and Shift
Both refer to genetic changesBoth refer to genetic changes DriftDrift: Minor changes in H and N : Minor changes in H and N
antigens; occur annually or every few antigens; occur annually or every few yearsyears
Shift:Shift: Major change (30% or more) in Major change (30% or more) in H and/or N antigens; “new” virus. H and/or N antigens; “new” virus. Important for starting pandemicsImportant for starting pandemics
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Influenza is GlobalInfluenza is Global
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PandemicsPandemics
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Required for Influenza PandemicRequired for Influenza Pandemic
““New” virus (antigenic shift)New” virus (antigenic shift)• Susceptible populationSusceptible population
Transmitted from animals to humansTransmitted from animals to humans
Cause disease in humansCause disease in humans
Efficient person to person transmissionEfficient person to person transmission
Bureau of Emergency Preparedness and Bureau of Emergency Preparedness and ResponseResponse
Influenza PandemicsInfluenza Pandemics
Have occurred for centuriesHave occurred for centuries Occur 11 to 42 years apartOccur 11 to 42 years apart
• Unpredictable but not randomUnpredictable but not random Attack rates of 10 to 40%Attack rates of 10 to 40% Excess mortalityExcess mortality But humanity survivesBut humanity survives
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2020thth Century Century
Bureau of Emergency Preparedness and Bureau of Emergency Preparedness and ResponseResponse
1918-19 Pandemic1918-19 Pandemic
aka Spanish Fluaka Spanish Flu H1N1 virusH1N1 virus, , Genetics: “avian Genetics: “avian
like”like” First cases in USAFirst cases in USA Global spread ~1 Global spread ~1
yryr Mortality 20-50 Mortality 20-50
millionmillion USA 500,000USA 500,000
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ImpactImpact
High mortalityHigh mortality Social disruptionSocial disruption
• BurialBurial• Public servicesPublic services• Events cancelledEvents cancelled
Spread along troop Spread along troop transport routestransport routes
Poor public health Poor public health responseresponse
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Mortality and “Waves”Mortality and “Waves”Taubenberger, Morens. EID. 2006;12: 15-22.Taubenberger, Morens. EID. 2006;12: 15-22.
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““the Mother of All Pandemics”the Mother of All Pandemics”Taubenberger, Morens.EID.2006;12:15-22Taubenberger, Morens.EID.2006;12:15-22
H1N1 1918 virus is the ancestor of H1N1 1918 virus is the ancestor of current influenza virusescurrent influenza viruses
Human and porcine lineage have Human and porcine lineage have some H1N1 genessome H1N1 genes
H3N2 virus retains some H1N1 genesH3N2 virus retains some H1N1 genes None of these as virulent as originalNone of these as virulent as original
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2020thth Century Century
Bureau of Emergency Preparedness and Bureau of Emergency Preparedness and ResponseResponse
1957-58 Influenza Pandemic1957-58 Influenza PandemicAsian InfluenzaAsian Influenza
H2N2 virusH2N2 virus: 3 new genes (H,N, PB1); : 3 new genes (H,N, PB1); 5 genes from 1918 H1N15 genes from 1918 H1N1
First cases in ChinaFirst cases in China Spread around world in 6 monthsSpread around world in 6 months 11stst wave: Fall’57 school age wave: Fall’57 school age 22ndnd wave: Jan’58 adults wave: Jan’58 adults 80,000 deaths in USA80,000 deaths in USA
• Very young and elderlyVery young and elderly
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2020thth Century Century
Bureau of Emergency Preparedness and Bureau of Emergency Preparedness and ResponseResponse
1968-69 Influenza Pandemic1968-69 Influenza PandemicHong Kong InfluenzaHong Kong Influenza
H3N2 VirusH3N2 Virus, 2 new , 2 new genes(H, PB1), 5 genes(H, PB1), 5 retained from retained from 1918. N2 from 1918. N2 from AsianAsian
Only 1 antigen Only 1 antigen shiftedshifted
Population has Population has some immunity to some immunity to N2N2
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H3N2 InfluenzaH3N2 Influenza
Lowest mortality of 20Lowest mortality of 20thth cent. cent. pandemicspandemics• 34,000 deaths in USA34,000 deaths in USA
U shaped mortality curveU shaped mortality curve
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Wave PhenomenonWave Phenomenon
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Where are we now?Where are we now?
H3N2 era. Seasonal influenza. H3N2 era. Seasonal influenza. Antigenic drift. Annual vaccine. Antigenic drift. Annual vaccine. Mortality ~36,000Mortality ~36,000
SURPRISESURPRISE 2003 H5 N1 avian virus2003 H5 N1 avian virus Highly pathogenic in birds, especially Highly pathogenic in birds, especially
chickenschickens Almost world wide spread Almost world wide spread
(asia,africa,and europe)(asia,africa,and europe)
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Humans and H5N1 HPAIHumans and H5N1 HPAI
Few cases in close contact with Few cases in close contact with chickenschickens• As of 7/14/06; 230 cases and 132 deathsAs of 7/14/06; 230 cases and 132 deaths
No efficient human to human No efficient human to human transmissiontransmission
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Required for Influenza PandemicRequired for Influenza Pandemic
““New” virus (antigenic shift)New” virus (antigenic shift)• Susceptible populationSusceptible population
Transmitted from animals to humansTransmitted from animals to humans
Cause disease in humansCause disease in humans
Efficient person to person transmissionEfficient person to person transmission
Bureau of Emergency Preparedness and Bureau of Emergency Preparedness and ResponseResponse
Be an optimist!Be an optimist! Power of scientific inquiry Power of scientific inquiry WHO global surveillance is good and WHO global surveillance is good and
getting bettergetting better Communication and cooperation Communication and cooperation
among nations is better since SARSamong nations is better since SARS Vaccine development and production Vaccine development and production
methods are on a fast trackmethods are on a fast track
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