Influenza Pandemic (H1N1) 2009

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1 Influenza Pandemic (H1N1) th Congress on Communicable Diseases Lisboa 29 January 2010 World Health Organization

2 Overview Since April 2009, first influenza pandemic of 21 st century underway Most extensive global preparations & coordination of international response in history But also fastest global spread of pandemic & some surprises What is the situation, main issues & challenges? 2

3 Previous Lessons Learned From History Major outbreaks affect world in many different ways Sheer health severity & social disruption of 1918 pandemic Rapid spread & economic impact of 2003 SARS Multisectoral impact of 2004 avian H5N1 influenza Penalties of being unprepared can be very high HIV / AIDS Must be vigilant at every step because always surprises and because conditions change Guillain Barre associated with 1976 Swine flu vaccination 3

4 World Health Organization Lead technical agency of United Nations for health 193 Member States that set global policy Secretariat that provides international technical support & coordination so policies can be implemented Headquarters Regional Offices Country Offices 4

5 WHO Has Paid Close Attention to Pandemic Influenza for Decades 1946 UN Committee starts planning global influenza surveillance 2 years before WHO Now >139 participating national laboratories in >100 countries Guidelines for national pandemic preparations (published in 1999, 2005, 2009) International Health Regulations in 2005 First international framework for coordinating detection, assessment, reporting & response to all potential international emergencies of of public health concern Global Action Plan for Pandemic Vaccine 5

6 Current Situation

7 First Unconfirmed Illness Reported in Early April 4 April: outbreak of ILI in Veracruz March April May June July August September October April: clusters of severe pneumonia in Mexico 7

8 First Laboratory Confirmations in Late April 21 April: 2 cases of H1N1 confirmed in California, USA 27 April: WHO phase 4 4 April: outbreak of ILI in Veracruz 29 April: WHO phase 5 Northern Hemisphere Number of specimens positive for influenza by subtypes (from 19 April to 26 September) March April Number of specimens positive for May June July August September October % influenza (39) 18 (40) 19 (38) 20 (38) 21 (38) 22 (36) 23 (34) 24 (29) 25 (45) 26 (37) 27 (40) 28 (38) 29 (40) 30 (36) 31 (39) 32 (37) 33 (38) 34 (39) 35 (38) 36 (34) 37 (28) 38 (24) 39 (24) Seasonnal A (H1) A (Not subtyped) B (Victoria lineage) Pandemic A (H1N1) Seasonnal A (H3) B (Yamagata lineage) B (Lineage not determined) Proportion of pandemic A (H1N1) 2009 to all influenza April: clusters of severe pneumonia in Mexico 23 April: H1N1 confirmed in several patients in MX Source: FluNet 8

9 New H1N1 Virus Shown to have Originated from Animal Influenza Viruses (Garten, et al Science 2009) 9

pandemic declared; H1N1 in 74 countries March April May June July August September October WK 24: SA H3N2 peak 15-17

10 International Spread Moved Very Quickly 21 April: 2 cases of H1N1 confirmed in California, USA 1 July: H1N1 in 120 Countries 4 April: outbreak of ILI in Veracruz 27 April: WHO phase 4 29 April: WHO phase 5 11 June: WHO phase 6 pandemic declared; H1N1 in 74 countries March April May June July August September October WK 24: SA H3N2 peak April: clusters of severe pneumonia in Mexico 23 April: H1N1 confirmed in several patients in MX Wk 26: Argentina peak ILI activity 10

11 Current Epidemiological Situation Northern Hemisphere (January 2010) One summer peak & second large winter peak Respiratory disease returning to non-seasonal levels Southern Hemisphere One winter peak & so far no summer peak Ongoing sporadic cases Tropics Variable activity but decreasing overall. Western Africa appears largely spared. 11

12 Current Epidemiological Situation Most active areas Central & Eastern Europe North coast of Africa (January 2010) Parts of South Asia but declining Next few to several months represent a period of epidemiological uncertainty 12

13 Impact of H1N1 Pandemic

14 Younger Age Groups Most Often Infected (Chile, EU and EFTA, Japan, Panama, Mexico) Percent of cases 40% 35% 30% 25% 20% 15% 10% 5% 0% Age groups 14

15 Children <5 years Have Highest Hospitalization Rates (Australia, Chile, Argentina, New Zealand) 15

16 Pandemic Hospitalization Patterns in U.S. 16

17 Death Patterns from Pandemic & Seasonal Influenza are Different (Mexico 24 March- 29 April 2009) 2155 cases of severe pneumonia, 821 hospitalizations,100 deaths 87% of deaths and 71% of severe pneumonia cases aged 5-59 yrs 17

18 Pandemic Pediatric Deaths in US 18

19 Pandemic Influenza & the elderly Elderly least likely to get infected by pandemic H1N1 virus But elderly most likely to die if infected 19

20 Severe Outcomes Most people develop uncomplicated self resolving illness 50-80% of severe cases have underlying conditions Pregnancy, asthma or other lung disorders, cardiovascular, diabetes, immunosuppression, neurologic disorders Majority of deaths from severe viral pneumonia & multi organ failure Bacterial co-infection in minority at presentation Many severe cases & deaths occuring in previously healthy adults & less often children 20

21 Pregnancy and Pandemic Influenza Infected pregnant women account for 5-10% of pandemic hospitalizations 5 times higher than child bearing age group Infected pregnant women are more likely (up to 10 times) to require ICU care Although not consistently seen everywhere Neuzil et al. Amer J Epidmiol 148:1094, 1998; Dodds et al. Can Med Assoc J 176:463, 2007; Rasmussen et al. Emerg Infect Dis 14:95, 2008; ANZIC NEJM 361, 2009, JAMA Oct

22 Other Potential Risk Factors Is obesity a risk factor? No consensus for Severe Outcome? Obese patients in ICU not at more risk to die than non-obese Not clear if obesity an independent factor or marker for comorbid conditions like diabetes Are indigenous populations at higher risk? Increased hospitalizations a consistent finding Difficult to tease out basis 22

23 Burden on Health Care System Higher than normal outpatient visits in many places In New Zealand, levels 3 times "normal" year Uncertain how much due "worried sick" Overall general hospital admissions not excessive But high in specific age groups Greatest pressure reported by intensive care units Severe ARDS requiring mechanical ventilation Levels 4 15 times usual influenza season for 1-2 months Longer than usual duration of stay ANZIC NEJM, Oct 2009, WHO internal report

24 Pandemic H1N1 Virus

25 Pandemic (H1N1) 2009 Virus Genetically & antigenically very different from seasonal H1N1 influenza viruses Quadruple reassortant Antibodies to seasonal H1N1 do not react to pandemic H1N1 viruses Current viruses remain antigenically & genetically similar to pandemic vaccine virus (A/California/7/2009) No known genetic sequence markers distinguish viruses from severe & mild cases D222G mutation occurs sporadically Reported in <1.8% of all (7% of fatal) cases but importance unclear 25

26 Antiviral Drug Sensitivities Most pandemic viruses resistant to amantadine & rimantadine Most sensitive to neuraminidase inhibitors (oseltamivir, zanamivir) Small minority (199 viruses) resistant to oseltamivir No known association with drug use / P-P-T Associated with postexposure prophylaxis Associated with treatment Immunosuppressed patients 26

27 Pandemic Viruses Predominating Over Seasonal Influenza Viruses in All Regions Adapted from Source: 27

28 WHO's Actions

29 Early and Continuing WHO Focus Ongoing assessment & communications International coordination Strong emphasis on non-pharmacological measures Respiratory hygiene, self-isolation if ill, home care. Support to countries including guidance, antiviral drugs, outbreak support, technical expertise, vaccines. 29

30 Pandemic Vaccines Given nature of threat, work began immediately on developing pandemic vaccines Before pandemic started, estimated time was 4-6 months to first doses 30

Several Types of Licensed Monovalent Pandemic Influenza A (H1N1) 2009 Vaccines (Source: IFPMA-IVS) Baxter (EMEA) Ommnivest (Hungary) 8 manufacturers, (China) *CSL

31 Several Types of Licensed Monovalent Pandemic Influenza A (H1N1) 2009 Vaccines (Source: IFPMA-IVS) Baxter (EMEA) Ommnivest (Hungary) 8 manufacturers, (China) *CSL (Australia; US) *Novartis (US) *Novartis+M59 adjuvant (EMEA) *MedImmune (US) Microgen (Russia) *Sanofi Pasteur (US) Green Cross (Korea) *GSK ASO3 (EMEA, Canada) * Donated to WHO 31

32 SAGE Recommendations on Use of Pandemic Vaccine (7 July 2009) First front-line health care workers (1-2% of population) to protect the health care system Then other specific groups to reduce morbidity and mortality pregnant women, individuals aged of >6 months with one of several chronic medical conditions Healthy young adults (aged >15 years and <49 years) Healthy children. Healthy adults aged >49 years and <65 years Healthy adults aged >65 years WER, 24 JULY 2009, No. 30, 2009, 84, , 32

33 Uneven International Access & Distribution of Pandemic Vaccine 35 Number of countries (cumulative) High Income Middle Income Low Income 31% 5 20% 49% 0 Sept Oct 1-15 Oct Nov 1-15 Nov Pandemic Vaccine Distribution World economies 1 1 World Bank classification

34 Major Effort to Make Vaccines Available for Developing Countries Call for "Global Solidarity" by Secretary General of UN and Director General of WHO 95 low to middle income countries without access identified Require about 200 million doses (plus syringes etc) to cover about 10% of their populations 200 million doses now pledged to WHO & first shipments started in January 34

35 Safety of Pandemic H1N1 vaccines in Large-Scale Usage Very high level of international scrutiny & information exchange Estimated >200 million doses administered since Sept 2009 Relatively few local & systemic reactions reported so far Number of severe events small, mainly allergic reactions Small number of deaths reported around time of vaccination So far from unrelated causes So far, no unexpected adverse effects for any H1N1 vaccines used in population-level immunization programmes 35

36 Concluding Comments Strong scientific documentation of emergence, spread & impact of H1N1 pandemic Level of preparedness & international coordination greatest in history yet many gaps & areas to improve Several important issues were anticipated Difficulty of stopping the pandemic when first emerged Very rapid international spread of virus Central role of communications Limited access to critical supplies by poorer countries 36

37 Concluding Comments Certain findings were very surprising Effectiveness of one dose of vaccine Future course & severity of a pandemic cannot be predicted at start Could range anywhere from "mild" to "severe" Final impact of this pandemic remains unknown In face of uncertain severity, "precautionary principle" provides populations with greatest safety net 37

38 THANK YOU 38

Situation Update Pandemic (H1N1) August 2009

Situation Update Pandemic (H1N1) 2009 31 August 2009 Timeline pandemic (H1N1) 2009 April 12: an outbreak of influenza-like illness in Veracruz, Mexico reported to WHO April 15-17: two cases of the new