A Comparative Analysis of Influenza Vaccination Programs
Shweta Bansal1, Babak Pourbohloul2, Lauren Ancel Meyers3,4* 1 Computational and Applied Mathematics, University of Texas Austin, Austin, Texas, United States of America, 2 UBC Centre for Disease Control, University of British Columbia, Vancouver, British Columbia, Canada, 3 Section of Integrative Biology and Institute for Cellular and Molecular Biology, University of Texas Austin, Austin, Texas, United States of America, 4 External Faculty, Santa Fe Institute, Santa Fe, New Mexico, United States of America
Background
The threat of avian influenza and the 2004–2005 influenza vaccine supply shortage in the United States have sparked a debate about optimal vaccination strategies to reduce the burden of morbidity and mortality caused by the influenza virus.
Methods and Findings
We present a comparative analysis of two classes of suggested vaccination strategies: mortality-based strategies that target high-risk populations and morbidity-based strategies that target high-prevalence populations. Applying the methods of contact network epidemiology to a model of disease transmission in a large urban population, we assume that vaccine supplies are limited and then evaluate the efficacy of these strategies across a wide range of viral transmission rates and for two different age-specific mortality distributions.
We find that the optimal strategy depends critically on the viral transmission level (reproductive rate) of the virus: morbidity-based strategies outperform mortality-based strategies for moderately transmissible strains, while the reverse is true for highly transmissible strains. These results hold for a range of mortality rates reported for prior influenza epidemics and pandemics. Furthermore, we show that vaccination delays and multiple introductions of disease into the community have a more detrimental impact on morbidity-based strategies than mortality-based strategies.
Conclusions
If public health officials have reasonable estimates of the viral transmission rate and the frequency of new introductions into the community prior to an outbreak, then these methods can guide the design of optimal vaccination priorities. When such information is unreliable or not available, as is often the case, this study recommends mortality-based vaccination priorities.
Funding: We acknowledge the financial support of the Canadian Institutes of Health Research, the Santa Fe Institute, and a NASA Harriett G. Jenkins Fellowship to SB. The funding agencies had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Academic Editor: Bryan Grenfell, Pennsylvania State University, United States of America
Citation: Bansal S, Pourbohloul B, Meyers LA (2006) A Comparative Analysis of Influenza Vaccination Programs. PLoS Med 3(10): e387 doi:10.1371/journal.pmed.0030387
Received: October 13, 2005; Accepted: July 13, 2006; Published: October 3, 2006
Copyright: © 2006 Bansal et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abbreviations: CDC, United States Centers for Disease Control and Prevention
* To whom correspondence should be addressed. E-mail: laurenmeyers@mail.utexas.edu
