Research Article: Global influenza seasonality to inform country-level vaccine programs: An analysis of WHO FluNet influenza surveillance data between 2011 and 2016

Date Published: February 21, 2018

Publisher: Public Library of Science

Author(s): Laura P. Newman, Niranjan Bhat, Jessica A. Fleming, Kathleen M. Neuzil, Benjamin J. Cowling.

http://doi.org/10.1371/journal.pone.0193263

Abstract

By analyzing publicly available surveillance data from 2011–2016, we produced country-specific estimates of seasonal influenza activity for 118 countries in the six World Health Organization regions. Overall, the average country influenza activity period was 4.7 months. Our analysis characterized 100 countries (85%) with one influenza peak season, 13 (11%) with two influenza peak seasons, and five (4%) with year-round influenza activity. Surveillance data were limited for many countries. These data provide national estimates of influenza activity, which may guide planning for influenza vaccination implementation, program timing and duration, and policy development.

Partial Text

Seasonal influenza is a significant public health problem, and vaccination is the primary tool to reduce influenza morbidity and mortality[1,2]. The World Health Organization (WHO) recommends influenza vaccination of high risk groups, including pregnant women, children aged <5 years, adults aged ≥ 65 years, persons of all ages with chronic medical conditions, and health care workers[3,4]. In 2013, 40% of countries worldwide recommend influenza vaccination in their National Immunization Programs, although influenza vaccine dose distribution varies[5–7]. Between 2004 and 2013, influenza dose distribution rates were the highest in the Region of the Americas and European Region, and lowest in South-East Asia and African Regions[7]. One hundred thirty two countries reported influenza surveillance data to FluNet between 2011 and 2016. Overall, 118 (89%) of the 132 countries reported more than 50 cases per year for two or more years between 2011 and 2016 and were included in the analyses. In 2011, 109 (83%) of the 132 countries reported more than 50 cases; this fluctuated between 110 (83%) in 2012, 114 (86%) in 2013, 109 (83%) in 2014, 105 (80%) in 2015, and 119 (90%) in 2016. Some countries did not report influenza surveillance data to WHO FluNet in every year. The greatest increase in the number of countries reporting at least 50 positive influenza cases to WHO FluNet occurred in the African Region, where influenza surveillance expanded from 14 countries in 2010 to 22 countries in 2016[17,21]. In this report, using predefined inclusion criteria, we present an analysis of WHO FluNet influenza surveillance data from 118 countries between 2011 and 2016 to characterize seasonal patterns of influenza activity. Our methods can be easily adapted for individual country needs. We characterized patterns of influenza activity in 118 countries across all six WHO regions using influenza surveillance data reported between 2011 and 2016. By using transparent methods and publicly available data, our analysis can be replicated on an individual country basis and updated as local surveillance systems mature. The timing, duration, and peak of influenza activity is an essential component in planning an influenza program and can be used to guide or refine national vaccination strategies. Overall, this country-specific characterization may be useful for countries aiming to introduce, scale-up, or align influenza vaccination programs with seasonal influenza trends.   Source: http://doi.org/10.1371/journal.pone.0193263

 

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