Seasonal Incidence of Symptomatic Influenza in the United States. (1st December 2017)

• Record Type: Journal Article
• Authors: Tokars, Jerome I; Olsen, Sonja J; Reed, Carrie
• Is Part Of: Clinical infectious diseases. Volume 66:Number 10(2018)
• Page Start: 1511
• Page End: 1518
• Publication Date: 2017-12-01
• Subjects: influenza -- incidence -- meta-analysis -- statistical estimation -- seasonal influenza incidence; Communicable diseases -- Periodicals; 616.905
• DOI: 10.1093/cid/cix1060
• Languages: English
• ISSNs: 1058-4838

Abstract

Abstract : The Centers for Disease Control and Prevention estimates that, during 2010–2016, the incidence of symptomatic influenza among the existing mix of vaccinated and unvaccinated United States residents, including both medically attended and nonattended infections, was approximately 8% and varied from 3% to 11% among seasons. Abstract: Background: The seasonal incidence of influenza is often approximated as 5%–20%. Methods: We used 2 methods to estimate the seasonal incidence of symptomatic influenza in the United States. First, we made a statistical estimate extrapolated from influenza-associated hospitalization rates for 2010–2011 to 2015–2016, collected as part of national surveillance, covering approximately 9% of the United States, and including the existing mix of vaccinated and unvaccinated persons. Second, we performed a literature search and meta-analysis of published manuscripts that followed cohorts of subjects during 1996–2016 to detect laboratory-confirmed symptomatic influenza among unvaccinated persons; we adjusted this result to the US median vaccination coverage and effectiveness during 2010–2016. Results: The statistical estimate of influenza incidence among all ages ranged from 3.0%–11.3% among seasons, with median values of 8.3% (95% confidence interval [CI], 7.3%–9.7%) for all ages, 9.3% (95% CI, 8.2%–11.1%) for children <18 years, and 8.9% (95% CI, 8.2%–9.9%) for adults 18–64 years. Corresponding values for the meta-analysis were 7.1% (95% CI, 6.1%–8.1%) for all ages, 8.7% (95% CI, 6.6%–10.5%) for children, and 5.1% (95% CI, 3.6%–6.6%) for adults. Conclusions: The 2 approaches produced comparable results for children and persons of all ages. The statistical estimates are more versatile and permit estimation of season-to-season variation. During 2010–2016, the incidence of symptomatic influenza among vaccinated and unvaccinated US residents, including both medically attended and nonattended infections, was approximately 8% and varied from 3% to 11% among seasons.