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. 2025 Jun 17;20(6):e0326098.
doi: 10.1371/journal.pone.0326098. eCollection 2025.

Vaccine fatigue and influenza vaccination trends across Pre-, Peri-, and Post-COVID-19 periods in the United States using epic's cosmos database

Tyler B Nofzinger  1   2 , Timothy T Huang  1   2 , Christopher Eduard R Lingat  1   2 , Gaurang M Amonkar  1   2 , Emily E Edwards  1   2 , Albert Yu  1   3 , Alexander D Smith  1   4 , Nasser Gayed  1 , Heidi L Gaddey  1   2
Affiliations

Vaccine fatigue and influenza vaccination trends across Pre-, Peri-, and Post-COVID-19 periods in the United States using epic's cosmos database

Tyler B Nofzinger et al. PLoS One. .

Abstract

Introduction: Influenza vaccination is a critical public health measure, especially amidst the challenges of the COVID-19 pandemic. This study uses Epic's Cosmos database to analyze influenza vaccination trends across demographic groups in the United States, examining the effects of the COVID-19 pandemic and "vaccine fatigue" on influenza vaccination rates.

Methods: This retrospective cross-sectional study analyzes influenza vaccination rates pre- (1 May 2018-31 May 2019), peri- (1 May 2020-31 May 2021), and post-COVID-19 (1 May 2023-31 May 2024). A two-proportion z-test and Cohen's h test were calculated to assess statistical significance.

Results: Influenza vaccination rates increased peri-COVID (+1.99% point change, h = 0.04, p < 0.001) and decreased post-COVID (-6.41% point change, h = 0.14, p < 0.001) relative to pre-COVID. The largest changes were observed in the following groups: 5-18 year olds (-13.92% point change, h = 0.31, p < 0.001), 19-26 year olds (-9.91% point change, h = 0.25, p < 0.001), American Indian or Alaska Native (-8.11% point change, h = 0.18, p < 0.001), Other Races (-7.36% point change, h = 0.17, p < 0.001), White (-6.89% point change, h = 0.15, p < 0.001), and the South U.S. census region (-7.21% point change, h = 0.17, p < 0.001).

Conclusion: Post-pandemic influenza vaccination compliance decreased relative to pre-pandemic, especially among younger age groups, certain racial groups, and in the southern U.S. These findings suggest that the COVID-19 pandemic negatively impacted influenza vaccination compliance. While overall trends aligned with publicly available data, absolute counts may be under-reported within Epic due to incomplete documentation of vaccine administrations outside of Epic-affiliated systems.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Influenza vaccination rates during pre-, peri-, and post-COVID-19 periods.
See this image and copyright information in PMC

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