WHO PANDEMIC PHASES

INFLUENZA VIRUS

MILESTONES IN INFLUENZA1933Demonstration of virus transmission to ferrets Smith et al. 19331937Growth of influenza virus in hens eggs Francis & Magill 19371941Agglutination of erythrocytes by influenza Hirst 19411943Extensive clinical trials in USA showed vaccine was 70% effective Francis 19431945Vaccination of US Army showed consistent protectionFrancis et al. 19461945Licence of first influenza vaccine in USA

SPORADIC INFLUENZA

PANDEMIC INFLUENZA

SEASONAL INFLUENZA

SPORADIC INFLUENZA

PANDEMIC INFLUENZA

SEASONAL INFLUENZA

HUMAN CASES OF AVIAN INFLUENZAYear Subtype No. of Cases Location 1997 H5N1 18 (6 deaths) Hong Kong 1999 H9N2 2 (children ages 4 yr, 13 mo) Hong Kong 2002 H7N2 1 United States (Virginia) 2003 H5N1 2 (1 death) Hong Kong 2003 H7N7 89 (1 death) The Netherlands 2003 H7N2 1 New York 2003 H9N2 1 (child) Hong Kong 2003- (ongoing) H5N1 262/440 (60%) Vietnam, Thailand, Cambodia, Indonesia, China, Turkey, Iraq, Azerbaijan, Egypt etc2004 H7N3 2 Canada (British Columbia) 2004 H10N7 2 (infants) Egypt

SPORADIC INFLUENZA

PANDEMIC INFLUENZA

SEASONAL INFLUENZA

INFLUENZA PANDEMICS15101889 1890H2N21899 1900H3N21918 1919H1N1 Spanish flu1957 1958H2N2 Asian flu1968 1969H3N2 Hong Kong flu

SPORADIC INFLUENZA

PANDEMIC INFLUENZA

SEASONAL INFLUENZA

INFLUENZA PANDEMICS15101889 1890H2N21899 1900H3N21918 1919H1N1 Spanish flu1957 1958H2N2 Asian flu1968 1969H3N2 Hong Kong flu1977 H1N1

RECOMMENDED VACCINE FORMULATIONThe following strains have been recommended by the WHO for the 2009 Southern Hemisphere influenza season:-

A/Brisbane/59/2007 (H1N1) - like virus *

A/Brisbane/10/2007 (H3N2) - like virus **

B/Florida/4/2006 - like virus #

*A/South Dakota/6/2007 (an A/Brisbane/59/2007-like virus) is a current vaccine virus used in live attenuated vaccines**A/Brisbane/10/2007 and A/Uruguay/716/2007 (an A/Brisbane/10/2007-like virus) are current vaccine viruses#B/Florida/4/2006 and B/Brisbane/3/2007 (a B/Florida/4/2006-like virus) are current vaccine viruses

ONSET & DURATION OF INFLUENZA SEASON: 1985 - 2007Median onset:Week 23Range 15-28Median peak:Week 27Range 20-32Median duration:10 weeksRange 7-17

INFLUENZA VIRUS

(9 subtypes)(16 subtypes)

HAEMAGGLUTININSH1N1NEURAMINIDASESH2N2H3N3H4N4H5N5H6N6H7N7H8N8H9N9H10H11H12H13H14H15H16PANDEMICS1918H1N1SPANISH PANDEMIC1957H2N2ASIAN PANDEMIC1968H3N2HONG KONG PANDEMICH5N1AVIAN INFLUENZA

INFLUENZA PANDEMICS15101889 1890H2N21899 1900H3N21918 1919H1N1 Spanish flu1957 1958H2N2 Asian flu1968 1969H3N2 Hong Kong flu2009 - ? H1N1 v Swine flu/pandemic 2009

H1N11918/19 Pandemic1918

Detection rate**

Diagnosed and reported H1N1 influenza statistics

Infected individualsSymptomatically infectedReport to doctorDoctor takes specimenDiagnosed and reported H1N1 influenza statisticsAdequate specimen reaches laboratoryLaboratory test reliableReported to surveillance authority

PANDEMIC H1N1 DEATHS (31ST August 2009)TOTAL = 27

A) PREGNANCY:12 (44%)Stage:1st trimester13rd trimester10Puerperium1

Co-morbidityNone5 (42%)Under investigation1HIV4TB (only)1Obese + substance abuse1

Age distributionRange16-37

B)NON-PREGNANTTotal: 15Age range:0-53yr

Nil 3(20%)

b)Co-morbiditiesHIV 2(1 TB)Obesity 7(1 asthma, 2 cardiac, 1 diabetes)Diabetes 4(1 obesity, 1 hypertension)TB 1Premature 1

WHO PANDEMIC PHASES

CHARACTERISTICS OF PANDEMICSNovel virusIncreased transmissibility+/- increased virulenceAge shiftRelative non-seasonalityGeographic heterogeneityMultiple wavesHuman adaptation seasonal influenza

3. VIRULENCECFR:MEXICO0.4% (0.3 0.6%)

USA0.2%

SEASONAL 0.04-0.08%INFLUENZA 1918/1919 5.0% PANDEMIC H5N1 60%

INFLUENZA PANDEMICS15101889 1890H2N21899 1900H3N21918 1919H1N1 Spanish flu1957 1958H2N2 Asian flu1968 1969H3N2 Hong Kong flu

SEASONAL INFLUENZA 250 500,000DEATHS

> 50 million> 1 million~ 0.5 million

MILD

INFLUENZA PANDEMICS NO. OF WAVES1889 1890H2N21899 1900H3N21918 1919H1N1 2 or 31957 1958H2N2 31968 1969H3N2 2

a lot of known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns the ones we dont know we dont knowDonald Rumsfeld US Secretary of Defense

THE IMPONDERABLES - VIRAL? Further waves? Replace human seasonal H1N1? Reassort with human seasonal H1N1? Mutational resistance development? Reassort with human seasonal H3N2? Reassort with avian H5N1

THE IMPONDERABLES - HUMANTravelUrbanizationImmunosuppressionDisplaced personsMedical and scientific advances

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