Summary of input variables, by age group (95% confidence intervals in parentheses).

1Source: National Health Interview Survey (NHIS), United States, 2006–2011. The season-cumulative vaccine coverage rates in this table are for summary description only; model employs incremental monthly age-specific values. Estimates of the cumulative monthly proportion vaccinated through end of April of each season were developed using the Kaplan-Meier product limit method for receipt of most recent reported influenza vaccination; estimates based on the NHIS may differ from estimates from other data sources (http://www.cdc.gov/flu/professionals/vaccination/vaccinecoverage.htm).2Estimates for seasons 05/06 - 08/09 represent combined estimates from available studies each season and were calculated as averages weighted by the inverse variance of each study. Sources: 2005/06 season: Belongia 2009, Ohmit 2008, Skowronski 2007. 2006/07 season: Belongia 2009, Skowronski 2009. 2007/08 season: Monto 2009, Belongia 2011, Frey 2010. 2008/09 season: Skowronski 2010, Shay 2011. 2009/10 pandemic season: Griffin et al. 2011. 2010/11 season: Treanor et al. 2012. VE estimates for the 2010/11 season are age-specific. VE estimates for seasons 2005/06-2009/10 are not age-specific, except for a downward adjustment applied to the 65+ age group as follows: VE for the 65+ age group is assumed to be 70% of the VE for the younger age groups.3Source: U.S. Census Bureau, Population Division. Annual Estimates of the Resident Population by Sex and Five-Year Age Groups for the United States.4Source: Centers for Disease Control and Prevention Emerging Infections Program (EIP) 2005–2010. The season-cumulative EIP hospitalization rates in this table are for summary description only; model employs month-specific and age-specific values.5Estimated using EIP hospitalization rates adjusted for underreporting. The underreporting adjustment multiplier was obtained from Reed 2009 and presumed constant across seasons and age categories at 2.7(CI 1.7–4.5).6Based on the estimated number of hospitalizations and age-specific case-hospitalization ratios from Reed 2009.7Based on the estimated number of cases and medically-attended (MA) ratios. The MA ratios used for the 2009/10 season are age-specific; source: Biggerstaff 2012. Age-specific and season-specific MA ratios for the five preceding seasons (2005/06–2009/10) were not available and were presumed constant at 42.0%(CI 37.9%–48.5%); source: Kamimoto 2010.