State-level estimates of excess hospitalizations and deaths associated with influenza

Background National estimates of influenza burden may not reflect state-level influenza activity, and local surveillance may not capture the full burden of influenza. Methods To provide state-level information about influenza burden, we estimated excess pneumonia and influenza (P&I) and respiratory and circulatory (R&C) hospitalizations and deaths in Colorado from local hospital discharge records, death certificates, and influenza virus surveillance using negative binomial models. Results From July 2007 to June 2016, influenza was associated with an excess of 17 911 P&I hospitalizations (95%CI: 15 227, 20 354), 30 811 R&C hospitalizations (95%CI: 24 344, 37 176), 1,064 P&I deaths (95%CI: 757, 1298), and 3828 R&C deaths (95%CI: 2060, 5433). There was a large burden of influenza A(H1N1) among persons aged 0-64 years, with high median seasonal rates of excess hospitalization among persons aged 0-4 years. Persons aged >= 65 years experienced the largest numbers and highest median seasonal rates of excess hospitalization and death associated with influenza A (H3N2). The burden of influenza B was generally lower, with elevated median seasonal rates of excess hospitalization among persons aged 0-4 years and >= 65 years. Conclusions These findings complement existing influenza surveillance. Periodic state-level estimates of influenza disease burden may be useful for setting state public health priorities and planning prevention and control initiatives.