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Ben Schwartz, M.D. National Vaccine Program Office, U.S. Department of Health and Human Services

NVAC Meeting, July 19, 2005. Defining Priority Groups for Pandemic Vaccine & Antiviral Drugs: Risk Groups and Critical Infrastructure. Ben Schwartz, M.D. National Vaccine Program Office, U.S. Department of Health and Human Services. Background. Pandemic vaccine supply will be limited

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Ben Schwartz, M.D. National Vaccine Program Office, U.S. Department of Health and Human Services

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  1. NVAC Meeting, July 19, 2005 Defining Priority Groups for Pandemic Vaccine & Antiviral Drugs: Risk Groups and Critical Infrastructure Ben Schwartz, M.D. National Vaccine Program Office, U.S. Department of Health and Human Services

  2. Background • Pandemic vaccine supply will be limited • Expect only U.S.-produced vaccine in a pandemic • Estimate ~6 million doses/wk from U.S. manufacturing • Antiviral drug (neuraminidase inhibitor) supply also will be limited • U.S. supply chain for oseltamivir expected in late-2005 but will produce only ~15 million courses/yr • Stockpiled drugs will be major source of pandemic supply

  3. Background • Given limited supply, priority groups must be defined for receipt of early vaccine & antiviral drugs • Targeting the limited supply of vaccine and antiviral drug to high risk groups and persons providing critical infrastructure will help achieve pandemic response goals of: • Decreasing pandemic health impacts • Decreasing societal impacts • Limiting economic disruption

  4. Presentation Objectives • Present analysis of high risk groups for severe influenza disease and death in a pandemic to facilitate designation of priority groups • Define critical infrastructures and estimate population sizes in these groups

  5. Methodology • Definition of high-risk groups • Working group (Pascale Wortley & Ted Eickhoff, co-chair) analyzed data on risk groups in prior pandemics and interpandemic influenza • Definition of critical infrastructure • Working group (Carolyn Bridges, chair) assessed potential critical infrastructure groups • Collaboration with the Department of Homeland Security • Total industry populations were further analyzed to identify those who provide essential services

  6. Part 1: Risk groups for illness, hospitalization, and death

  7. Clinical Influenza Attack Rates, 1918 *approximations based on figure in Frost 1919—household surveys conducted Dec 1918

  8. Clinical Influenza Attack Rates, Fall 1957 *lab-confirmed

  9. Clinical Influenza attack rates, Nov 1968-Jan 1969 *weekly mean averages

  10. Pneumonia & Influenza (P & I) Mortality Rates, 1918 *Frost 1919, approximations based on figure

  11. P&I Mortality Rates (per 105), 108 Cities, Aug-Dec 1957 Age group Dauer 1958

  12. P&I Mortality Rates (per 105), 1968-69 Age group Luk, 2001

  13. Proportion of Excess P & I Deaths in Persons <65 y.o. in Influenza Pandemic & Inter-pandemic Seasons, 1918-95 Simonsen et al. JID 1998

  14. Hospitalizations and Deaths Among Persons >65 Yrs. Old, 1996-1998 Rate (per 105) *Renal disease, immunodeficiency, organ transplants, non-hematologic cancer Source: Hak 2002 CID

  15. Hospitalizations and Deaths per 10,000 Persons 15-64, 1973-1992 Range 36-76/10,000 Neuzil 1999 JAMA Neuzil 2003 JAIDS *HIV-HAART data: 1995-1999 *NS

  16. P & I Deaths by Number of High Risk Conditions - Oregon HMO Barker, Arch Intern Med 1982

  17. Previous Hospitalization as a Risk Factor for Severe Influenza • 39 – 46% of the elderly discharged for an influenza-associated respiratory condition had a recent hospitalization • 62 – 67% of those who died had a recent hospitalization • 6% of elderly persons were hospitalized during the influenza season Fedson, Annals of Internal Medicine 1992;116:550-5

  18. Risk Factors for P & I Hospitalization & Death During Influenza Season * Immunodeficiency and organ transplants Hak 2004 JID

  19. Specific Conditions: Bone Marrow Transplants • Limited studies (Nichols 2004, Whimbey 1994) , but both suggest high rates of complications. • Largest study (Nichols): 18/62 BMT pts with lab confirmed influenza had LRI; 6/62 died (5 of 6 had LRI) • Likely greater benefit from antiviral drugs than vaccine

  20. Risk of Pandemic Influenza Death in Pregnancy • Harris 1919: case series of pregnant women with influenza; 50% had pneumonia, and 50% CFR w/ pneumonia (7-9th months: 60% vs 1-6 m:45-53%). • Woolston 1918: 2154 pts admitted to Cook County Hospital; 50% of pregnant women died compared with 33% of other pts. • Greenberg 1958: NYC mortality data fall 1957; 47 P&I deaths in women 15-49; 22/47 (47%) were pregnant.

  21. Size of Potential Priority Groups for Pandemic Vaccine & Antiviral Drugs *groups may overlap

  22. Part 2: Critical Infrastructures for a pandemic response

  23. Critical Infrastructure: Potential Vaccine and Antiviral Target Groups Definition of infrastructure: “The framework of interdependent networks and systems comprising identifiable industries, institutions and distribution capabilities that provide a reliable flow of products and services essential to the defense and economic security of the of the US, the smooth functioning of government at all levels, and society as a whole.” President’s Commission on Critical Infrastructure Protection, Critical Foundations Protecting America’s Infrastructure, October 1997

  24. Approach to Define Critical Infrastructures & Populations • Focus on occupations/industries that contribute to achieving pandemic response goals • Consider critical infrastructure definitions from other sources (White House, Congress, Canadian pandemic plan) and experience from preparedness exercises • Defined population sizes from Bureau of Labor Statistics data • Honed populations based on input from DHS

  25. Key Issues and Limitations • Importance of networks and supply chains • E.g., what industries/personnel are required to assure that medical supplies reach healthcare facilities and food reaches persons in cities? • Estimates of absenteeism during a pandemic • What proportion of persons will miss work and can function be preserved with this work loss? • Experience from prior pandemics is not informative and no comparable health emergencies have occurred

  26. Estimate of Days Lost From Work Due to Illness in Self or Family • Modeled lost work days from illness using FluAid and FluSurge (based on 1957/1968 pandemics) and 2000 Census • Inputs: • Days lost from work due to illness • Days lost from work due to caring for family member • Employment rate, marriage rate, work days per month • Assumed outbreak period 8 weeks and 25% influenza illness rate as base-case Xinzhi Zhang, MD PhD and Martin I. Meltzer, PhD MS

  27. Model Inputs and Total Lost Work Days Days of work for own illness Days caring for others

  28. Proportion of Work Days Lost Due to Pandemic Influenza Scenario B (10%) 12% 10% Scenario A (4.8%) 8% 6% 4% 2% 0% 1 8 15 22 29 36 43 50 Days of outbreak

  29. Limitations of Work Loss Model • Wide range of estimates for of work day loss • Largely unknown from literature • For interpandemic influenza, lost work days per illnfluenza-like illness average 1 day in US studies • Impacts are likely to vary between communities, industries, and worksites • Estimates are based on less severe pandemics • Some experts felt that peak would be sharper than in the model resulting in greater proportion of work loss at the height of the outbreak

  30. Potential Critical Infrastructures to Achieve Pandemic Response Goals • Decrease pandemic health impacts • Health care workers • Public health workers & other pandemic responders • Health decision makers • Decrease health and societal impacts • Transportation (food & medical supplies; people) • Utilities (electricity, gas, water) • Public safety (police, fire, and corrections) • Mortuary • Sanitation • Military and government

  31. Health Care Workers: Categories and Populations Bureau of Labor Statistics, 2003

  32. Proposed Critical Infrastructure for Pandemic Vaccine & Antiviral Priority • Inpatient and outpatient health care workers • Estimate that ~2/3 have direct patient contact or are essential for quality care • N = 8,375,000 • Emergency medical services • Assume all are essential in a pandemic (820,000) • Total number of HCWs/EMS = 9,195,000

  33. Proposed Critical Infrastructure for Pandemic Vaccine & Antiviral Priority Total = 9,008,000

  34. Future Work to Be Done • Hone definitions of infrastructure groups and population sizes • Further define specific sections of each group critical for maintenance of function • Evaluate ability to absorb some work loss and surge capacity • Identify additional groups along supply chains that may also need to be prioritized (e.g. critical food groups needed to supply food for transportation) • Consider implementation issues • How can persons in target groups be identified for vaccination and antiviral treatment?

  35. Acknowledgements & Thanks • Pascale Wortley, Ted Eickhoff & the pandemic impact working group • Carolyn Bridges & the critical infrastructure group • Dale Brown, Department of Homeland Security • Elizabeth Falcone, NVPO intern • Xinzhi Zhang & Martin Meltzer, CDC/modeling

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