Intermediate levels of vaccination coverage may minimize seasonal influenza outbreaks

• Type of Material: Article
• Authors: Veronika I. Zarnitsyna, Emory University; Irina Bulusheva, Moscow Institute of Physics and Technology; Andreas Handel, University of Georgia; Ira M. Longini, University of Florida; M. Elizabeth Halloran, Fred Hutchinson Cancer Research Center; Rustom Antia, Emory University
• Language: English
• Date: 2018-06-01
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2018 Zarnitsyna 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.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pone.0199674
• Title of Journal or Parent Work: PLoS ONE
• ISSN: 1932-6203
• Volume: 13
• Issue: 6
• Start Page: e0199674
• End Page: e0199674
• Grant/Funding Information: MIDAS-U54GM111274 National Institute of General Medical Sciences U19 AI117891 National Institute of Allergy and Infectious Diseases R37 AI32042 National Institute of Allergy and Infectious Diseases The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
• Research Categories: Health Sciences, Immunology; Biology, Biostatistics

Abstract

For most pathogens, vaccination reduces the spread of the infection and total number of cases; thus, public policy usually advocates maximizing vaccination coverage. We use simple mathematical models to explore how this may be different for pathogens, such as influenza, which exhibit strain variation. Our models predict that the total number of seasonal influenza infections is minimized at an intermediate (rather than maximal) level of vaccination, and, somewhat counter-intuitively, further increasing the level of the vaccination coverage may lead to higher number of influenza infections and be detrimental to the public interest. This arises due to the combined effects of: competition between multiple co-circulating strains; limited breadth of protection afforded by the vaccine; and short-term strain-transcending immunity following natural infection. The study highlights the need for better quantification of the components of vaccine efficacy and longevity of strain-transcending cross-immunity in order to generate nuanced recommendations for influenza vaccine coverage levels.