Effectiveness and Cost-Effectiveness of Expanded Antiviral Prophylaxis and Adjuvanted Vaccination Strategies for an Influenza A (H5N1) Pandemic

doi:10.1059/0003-4819-151-12-200912150-00156

Effectiveness and Cost-Effectiveness of Expanded Antiviral Prophylaxis and Adjuvanted Vaccination Strategies for an Influenza A (H5N1) Pandemic

Nayer Khazeni, MD, MS;
David W. Hutton, MS;
Alan M. Garber, MD, PhD; and
Douglas K. Owens, MD, MS

From Stanford University and Stanford University Medical Center, Stanford, California, and Veterans Affairs Palo Alto Health Care System, Palo Alto, California.

Abstract

Background: The pandemic potential of influenza A (H5N1) virus is a prominent public health concern of the 21st century.

Objective: To estimate the effectiveness and cost-effectiveness of alternative pandemic (H5N1) mitigation and response strategies.

Design: Compartmental epidemic model in conjunction with a Markov model of disease progression.

Data Sources: Literature and expert opinion.

Target Population: Residents of a U.S. metropolitan city with a population of 8.3 million.

Time Horizon: Lifetime.

Perspective: Societal.

Interventions: 3 scenarios: 1) vaccination and antiviral pharmacotherapy in quantities similar to those currently available in the U.S. stockpile (stockpiled strategy), 2) stockpiled strategy but with expanded distribution of antiviral agents (expanded prophylaxis strategy), and 3) stockpiled strategy but with adjuvanted vaccine (expanded vaccination strategy). All scenarios assumed standard nonpharmaceutical interventions.

Outcome Measures: Infections and deaths averted, costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness.

Results of Base-Case Analysis: Expanded vaccination was the most effective and cost-effective of the 3 strategies, averting 68% of infections and deaths and gaining 404 030 QALYs at $10 844 per QALY gained relative to the stockpiled strategy.

Results of Sensitivity Analysis: Expanded vaccination remained incrementally cost-effective over a wide range of assumptions.

Limitations: The model assumed homogenous mixing of cases and contacts; heterogeneous mixing would result in faster initial spread, followed by slower spread. We did not model interventions for children or older adults; the model is not designed to target interventions to specific groups.

Conclusion: Expanded adjuvanted vaccination is an effective and cost-effective mitigation strategy for an influenza A (H5N1) pandemic. Expanded antiviral prophylaxis can help delay the pandemic while additional strategies are implemented.

Primary Funding Source: National Institutes of Health and Agency for Healthcare Research and Quality.

Article and Author Information

Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of the Agency for Healthcare Research and Quality.
Acknowledgment: The authors thank the reviewers for their extremely thorough and helpful reviews; Anne Berry, JD, MBA, and Edward Sheen, MD, MBA, of Stanford University for their contributions to the early design of this project; Sara Cody, MD, of the Santa Clara County Public Health Department for her assistance with the design of our Influenza Care Center; Mark Holodniy, MD, of the Veterans Affairs Palo Alto Healthcare System for his assistance with cost information; and Michael Gould, MD, MS, of Stanford University, Timothy Uyeki, MD, MPH, MPP, of the Centers for Disease Control and Prevention, and David Fedson, MD, for their thoughtful reviews of an earlier version of the manuscript. None of the listed individuals received additional compensation in association with this work.
Grant Support: By the National Institutes of Health (Stanford University T32 HL007948, Dr. Khazeni), the Agency for Healthcare Research and Quality (1 F32 HS018003-01A1, Dr. Khazeni), the Helena Anna Henzl Gabor Travel Award (Dr. Khazeni), the National Institute on Drug Abuse (2 R01 DA15612-016, Dr. Owens), a Stanford Graduate Fellowship (Mr. Hutton), and the Department of Veterans Affairs (Drs. Owens and Garber).
Potential Conflicts of Interest: None disclosed.
Reproducible Research Statement: An annotated version of the model is available in Appendix 1 so that others can test our findings and conclusions.
Requests for Single Reprints: Nayer Khazeni, MD, MS, Division of Pulmonary and Critical Care Medicine, Stanford University Medical Center, 300 Pasteur Drive, H3143, Stanford CA 94305.
Current Author Addresses: Dr. Khazeni: Division of Pulmonary and Critical Care Medicine, Stanford University Medical Center, 300 Pasteur Drive, H3143, Stanford, CA 94305.
Mr. Hutton: 496 Terman Engineering Center, Stanford University, Stanford, CA 94305.
Drs. Garber and Owens: Center for Health Policy and Center for Primary Care and Outcomes Research, Stanford University, 117 Encina Commons, Stanford, CA 94305-6019.
Author Contributions: Conception and design: N. Khazeni, D.W. Hutton, A.M. Garber, D.K. Owens.
Analysis and interpretation of the data: N. Khazeni, D.W. Hutton, A.M. Garber, D.K. Owens.
Drafting of the article: N. Khazeni, D.W. Hutton, A.M. Garber, D.K. Owens.
Critical revision of the article for important intellectual content: N. Khazeni, D.W. Hutton, A.M. Garber, D.K. Owens.
Final approval of the article: N. Khazeni, D.W. Hutton, A.M. Garber, D.K. Owens.
Provision of study materials or patients: N. Khazeni.
Statistical expertise: N. Khazeni, D.W. Hutton, A.M. Garber, D.K. Owens.
Obtaining of funding: N. Khazeni.
Administrative, technical, or logistic support: N. Khazeni, A.M. Garber.
Collection and assembly of data: N. Khazeni, D.W. Hutton.