Comparison of healthcare resource use and cost between influenza and COVID-19 vaccine coadministration and influenza vaccination only

Abstract

ObjectiveTo compare healthcare recourse utilizations (HCRU) and all-cause medical costs among individuals 50 years or older who received both influenza and COVID-19 vaccines on the same day and those that received influenza vaccine onlyMethodsWe conducted a retrospective cohort study leveraging Optum’s de-identified Clinformatics® DataMart from 8/31/2021 to 7/31/2023. Individuals 50 years or older continuously enrolled in health plans for one year prior and until 7/31/2023 were included in the study. Subjects were categorized into 2 cohorts based on their vaccination status between 8/31/2022 and 1/31/2023: receiving influenza and COVID-19 vaccine on same day (co-admin cohort) and receiving influenza vaccine only (influenza cohort). The association between vaccination status and all-cause, influenza-related, COVID-related, pneumonia-related, and cardiorespiratory-related hospitalization, as well as outpatient or emergency room visits and all-cause medical costs was estimated by weighted generalized linear models, adjusting for confounding by stabilized inverse probability of treatment weighting.Results613,156 (mean age: 71) and 1,340,011 (mean age: 72) individuals were included in the co-admin and influenza cohort respectively. After weighting, the baseline characteristics were balanced between cohorts. The co-admin cohort was at statistically significant lower risk of all-cause (RR: 0.95, 95%CI: 0.93-0.96), COVID-19-related (RR: 0.59, 95%CI: 0.56-0.63), cardiorespiratory-related (RR: 0.94, 95%CI: 0.93-0.96) and pneumonia-related (RR: 0.86, 95%CI: 0.83-0.90) hospitalization but not influenza-related hospitalizations (RR: 0.91, 95%CI: 0.81, 1.04) compared to influenza cohort. Co-administration was associated with 3% lower all-cause medical cost (cost ratio: 0.974, 95% CI: 0.968, 0.979) during the follow-up period compared to receiving influenza vaccine only.ConclusionReceiving both COVID-19 and influenza vaccines on the same day in comparison to receipt of influenza vaccine only was associated with reduced risk of HCRU, especially COVID-19 related hospitalization and all-cause medical costs. Interventions that increase vaccine coverage, particularly for COVID-19 might have public health and economic benefits.