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. 2021 May:25:20.154.
doi: 10.7812/TPP/20.154.

Trends in Influenza Vaccine Uptake and Severe Influenza-Related Outcomes at Kaiser Permanente Southern California, 2007-2017

In-Lu Amy Liu  1 , Hilary C Tanenbaum  1 , Lei Qian  1 , Lina S Sy  1 , Wansu Chen  1 , Steven J Jacobsen  1
Affiliations

Trends in Influenza Vaccine Uptake and Severe Influenza-Related Outcomes at Kaiser Permanente Southern California, 2007-2017

In-Lu Amy Liu et al. Perm J. 2021 May.

Abstract

Introduction: Major efforts to increase influenza vaccine uptake among Kaiser Permanente Southern California (KPSC) members have been undertaken in recent years. However, whether these improvements translate to a decline in severe influenza-related outcomes has not been examined. We aimed to understand the impact of the influenza vaccination program at KPSC by examining influenza vaccine uptake and 3 severe influenza-related outcomes.

Methods: We conducted an ecologic trend analysis to understand influenza vaccine uptake and influenza-related hospitalization, intensive care unit (ICU) admission, and mortality for each influenza season (2007-2017). The same cohort was followed from the influenza season to the noninfluenza season immediately afterward while using the noninfluenza season as the comparison group. We also assessed the within-season correlation between influenza vaccine uptake and influenza-related outcomes.

Results: Influenza vaccine uptake rose from 23.9% to 45.5%, and all 3 influenza-related outcome rates declined (hospitalization: 35.4-26.8/10,000 patients; ICU: 5.9-5.2/10,000 patients; and mortality: 3.4-2.3/10,000 patients). Influenza vaccine uptake was negatively correlated with hospitalization (-0.32, p < 0.001) and mortality (-0.29, p = 0.001). However, once we adjusted for the noninfluenza season, the results of the correlation analysis were no longer statistically significant.

Conclusion: Although we could not establish a statistically significant inverse relationship between influenza vaccination and severe influenza-related outcomes over the study period, our findings indicate an overall decline in influenza-related outcomes over the study period, suggesting improvements in both preventive and acute care quality at KPSC.

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Conflict of interest statement

Disclosure Statement: In-Lu Amy Liu, MS, reports no conflicts of interest. Hilary C Tanenbaum, PhD, MS, MPH, received research contract grants from companies of GlaxoSmithKline and Modulated Imaging. Lei Qian, PhD, received a research contract grant from GlaxoSmithKline. Lina S Sy, MPH, received research contract grants from companies of GlaxoSmithKline, Dynavax, and Novavax. Wansu Chen, PhD, MS, reports no conflicts of interest. Steven J Jacobsen, MD, PhD, reports no conflicts of interest xist.

Figures

Figure 1.
Figure 1.
Influenza vaccine uptake, 2007-2017§, Kaiser Permanente Southern California. § Influenza vaccination period defined as September-April.*Overall rates were standardized for age, sex, and race/ethnicity using data from the last season (2016-17).
Figure 2.
Figure 2.
Rates of influenza-related outcomes per 10,000 patients, 2007-2017, Kaiser Permanente Southern California.
See this image and copyright information in PMC

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