Occurrence, Timing, Intensity, and Risk Factors of Recurrent Waves in the 2009 Influenza Pandemic: A multi-country comparison using WHO FluNet surveillance data

<p>The 2009 influenza A(H1N1)pdm09 virus first appeared in Mexico in March and resulted in the first global pandemic since 1968. This pandemic caused at the very least 18, 000 deaths worldwide over the approximately 17-month pandemic period, and was characterized by an atypical and disproportionate age distribution, mostly sparing adults over 60. While this pandemic was relatively mild in terms of mortality in comparison to previous pandemics, the burden of infection was felt globally and the pandemic virus continued to circulate even after WHO declared the pandemic over in August, 2010. Several studies have already attempted to analyze influenza burden during the 2009 pandemic period and during recurring waves of this virus in individual countries. However, none attempted a comparison of A(H1N1)pdm09 activity between countries in different climates and regions, after the initial 2009-10 pandemic period.</p> <p>The purpose of this endeavor is to conduct such an analysis and determine what country factors (using World Bank country indicators) may explain differences in timing and intensity, of pandemic wave activity during 2009-2012. To accomplish this, I accessed the World Health Organization’s (WHO) FluNet laboratory surveillance database to select and analyze a cohort of countries providing reliable virological surveillance data. Multiple regression modeling and geographic analysis were used and results indicated that all countries experienced multiple waves of A(H1N1)pdm09 infection, and that several countries actually experienced a larger proportion of cases after the pandemic had ended. In addition, several factors including economic indicators (GNI, measles immunizations, etc.), regional location (Americas, Europe, and South East Asia), and prevalence of female smoking were associated with a higher number of pandemic influenza waves. Finally, I present several recommendations based on the analysis findings, including:</p> <p>1. Proposed Improvements for WHO FluNet surveillance system;</p> <p>2. Improving post-pandemic surveillance and public health efforts; and</p> <p>3. Suggested findings and techniques deserving of continued research.</p> <p> </p> <p>Special thanks and consideration go to Dr. Lone Simonsen for her continuous support and guidance throughout the planning, research, and writing of this thesis project. I would also like to give a special thanks to the World Health Organization’s (WHO) Global Influenza Surveillance team, specifically Dr. Julia Fitzner, Dr. Anthony Mounts, and Dr. Katelijn Vandemaele, for their overall guidance and assistance with the WHO FluNet respiratory surveillance data.