Characteristics of Repeated Influenza Vaccination Among Older U.S. Adults

Characteristics and factors of repeated influenza vaccination among elderly individuals in Shanghai, China from 2020 to 2022

Elderly individuals face a high risk of hospitalization and death related to influenza, thus prioritizing them for influenza vaccination. Due to variations in the influenza virus and waning protective antibodies, annual influenza vaccination is recommended. However, research on repeated influenza vaccination among elderly individuals in China is limited. From 2020 to 2022, the average influenza vaccination coverage among registered elderly individuals in Shanghai was 4.1%, showing a declining trend over time. In 2020, the rate of repeated influenza vaccination among elderly individuals was 28.35%, which rose to almost two-thirds both in 2021 and 2022. No increased risk of adverse events following immunization was observed after repeated influenza vaccination during this period. Our study also found that elderly individuals with Shanghai household registration, managed by community clinics, and older age tended to receive more doses of repeated influenza vaccination throughout the period from 2020 to 2022. Increasing influenza vaccine coverage among elderly individuals in Shanghai is both urgent and challenging. Health authorities should intensify educational and promotional campaigns to encourage uptake of annual repeated influenza vaccination among elderly individuals.

[Once vaccinated, always vaccinated? A claims data analysis on repeated influenza vaccinations among individuals aged ≥ 60 years]

BACKGROUND

The Standing Committee on Vaccination recommends the seasonal influenza vaccination as a standard vaccination for individuals aged ≥ 60 years and as an indication vaccination independent of age. Empirical data on repeated vaccination are not available for Germany. The aim of this study was therefore to investigate the frequency and influencing factors of repeated vaccinations.

METHODS

We conducted a longitudinal retrospective observational study with claims data from ≥ 60‑year-olds insured with the statutory health insurance AOK Plus in Thuringia between 2012 and 2018. The number of seasons with influenza vaccination was described and the association with various individual characteristics was analysed in a regression model.

RESULTS

Included were 103,163 individuals with at least one influenza vaccination in the 2014/2015 season, of whom 75.3% had been vaccinated in ≥ 6 of 7 seasons. We found repeated vaccinations more frequently among nursing home residents (rate ratio (RR) 1.27), individuals with increased health risk due to underlying diseases (RR 1.21) and higher age groups (vs. 60-69 years: RR 1.17-1.25). With each additional year of participating in a disease management program, the number of vaccinations increased (RR 1.03). Women (RR 0.91), individuals with nursing care level 1 (vs. no nursing care level: RR 0.90) and people with a comorbidity (vs. no comorbidity: RR 0.97) were less likely to receive repeated vaccinations.

DISCUSSION

A large proportion of individuals aged ≥ 60 years who have been vaccinated against influenza once is likely to repeatedly receive vaccinations. In accordance with vaccination recommendations, nursing home residents and in particular individuals with an increased health risk are vaccinated repeatedly. General practitioners play a central role: non-acute patient contacts should be used to offer vaccinations, especially to women and individuals in need of care who are living at home.

Geographic variation in influenza vaccination among U.S. nursing home residents: A national study

Objectives

Estimates of influenza vaccine use are not available at the county level for U.S. nursing home (NH) residents but are critically necessary to guide the implementation of quality improvement programs aimed at increasing vaccination. Furthermore, estimates that account for differences in resident characteristics between counties are unavailable. We estimated risk‐standardized vaccination rates (RSVRs) among short‐ and long‐stay NH residents by U.S. county and identified drivers of geographic variation.

Methods

We conducted a retrospective cohort study utilizing 100% of 2013–2015 fee‐for‐service Medicare claims, Minimum Data Set assessments, Certification and Survey Provider Enhanced Reports, and Long‐Term Care: Facts on Care in the U.S. We separately evaluated short‐stay (<100 days) and long‐stay (≥100 days) residents aged 65 and older across the 2013–2014 and 2014–2015 influenza seasons. We estimated RSVRs via hierarchical logistic regression adjusting for 32 resident‐level covariates. We then used multivariable linear regression models to assess associations between county‐level NHs predictors and RSVRs.

Results

The study cohort consisted of 2,817,217 residents in 14,658 NHs across 2798 counties. Short‐stay residents had lower RSVRs than long‐stay residents (2013–2014: median [interquartile range], 69.6% [62.8–74.5] vs 84.0% [80.8–86.4]), and there was wide variation within each population (range, 11.4–89.8 vs 49.1–92.6). Several modifiable facility‐level characteristics were associated with increased RSVRs, including higher registered nurse to total nurse ratio and higher total staffing for licensed practical nurses, speech‐language pathologists, and social workers. Characteristics associated with lower RSVRs included higher percentage of residents restrained, with a pressure ulcer, and NH‐level hospitalizations per resident‐year.

Conclusions

Substantial county‐level variation in influenza vaccine use exists among short‐ and long‐stay NH residents. Quality improvement interventions to improve vaccination rates can leverage these results to target NHs located in counties with lower risk‐standardized vaccine use.