Relative Effectiveness of Cell-Cultured and Egg-Based Influenza Vaccines Among Elderly Persons in the United States, 2017–2018. (18th December 2018)

• Record Type: Journal Article
• Authors: Izurieta, Hector S; Chillarige, Yoganand; Kelman, Jeffrey; Wei, Yuqin; Lu, Yun; Xu, Wenjie; Lu, Michael; Pratt, Douglas; Chu, Steve; Wernecke, Michael; MaCurdy, Thomas; Forshee, Richard
• Is Part Of: Journal of infectious diseases. Volume 220:Number 8(2019)
• Page Start: 1255
• Page End: 1264
• Publication Date: 2018-12-18
• Subjects: influenza vaccine -- vaccine effectiveness -- relative vaccine effectiveness -- cell-cultured vaccine; Communicable diseases -- Periodicals; Diseases -- Causes and theories of causation -- Periodicals; Medicine -- Periodicals; Communicable Diseases -- Periodicals; Electronic journals; 616.9
• DOI: 10.1093/infdis/jiy716
• Languages: English
• ISSNs: 0022-1899

Abstract

Abstract: Background: The low influenza vaccine effectiveness (VE) observed during the A(H3N2)-dominated 2017–2018 season may be due to vaccine virus adaptation to growth in eggs. We compared the effectiveness of cell-cultured and egg-based vaccines among Medicare beneficiaries. Methods: Retrospective cohort study on Medicare beneficiaries aged ≥65 years who received an influenza vaccine (cell-cultured, egg-based quadrivalent; egg-based high-dose, adjuvanted, or standard-dose trivalent) during the 2017–2018 season. We used Poisson regression to evaluate relative VE (RVE) in preventing influenza-related hospital encounters. Results: Of >13 million beneficiaries, RVE for cell-cultured vaccines relative to egg-based quadrivalent vaccines was 10% (95% confidence interval [CI], 7%–13%). In a midseason interim analysis, this estimate was 16.5% (95% CI, 10.3%–22.2%). In a 5-way comparison, cell-cultured (RVE, 11%; 95% CI, 8%–14%) and egg-based high-dose (RVE, 9%; 95% CI, 7%–11%) vaccines were more effective than egg-based quadrivalent vaccines. Conclusions: The modest VE difference between cell-cultured and egg-based vaccines only partially explains the low overall VE reported by the Centers for Disease Control and Prevention, suggesting that egg adaptation was not the main contributor to the low VE found among individuals aged ≥65 years. The midseason interim analysis we performed demonstrates that our methods can be used to evaluate VE actively during the influenza season. Abstract : Among >13 million Medicare beneficiaries, the cell-cultured vaccine was more effective than the comparable egg-based vaccine during the 2017–2018 season. However, the marginal difference in effectiveness observed only partially explains the overall low vaccine effectiveness reported during the season.