BACKGROUND: Influenza contributes to excess healthcare utilization and morbidity in individuals with glomerular disease (GD). Immune responses to influenza vaccination in individuals with GD may be attenuated by immune dysregulation and immunosuppressant use. We evaluated the effectiveness of influenza vaccination among patients with GD.
METHODS: Individuals with incident primary GD were identified within the Merative MarketScan® Claims & Encounters database and followed across annual influenza seasons until disenrollment or 2020. Influenza vaccination, influenza and influenza-like infections, and covariates were ascertained using ICD-9/10-CM-based definitions from medical and prescription claims. Influenza seasons (2010-2019) were analyzed individually by comparing the incidence rates of infection in vaccinated and unvaccinated individuals. Propensity score weighting was used to balance the distribution of potential confounders across vaccination status. Cox proportional hazards models were used to estimate vaccine effectiveness (VE=1-hazard ratio). We then compared years with a close match between vaccine composition and circulating influenza strains (2010-2013, 2015-2018), with a mismatched “control” season (2014). We used a weighted Cox model with an interaction term between vaccination status and vaccine match grouping to estimate the relative VE in matched vs. mismatched seasons.
RESULTS: 46,010 influenza person-seasons were analyzed from 17,219 individuals with GD (mean age 45 years (SD 17), 43% female), including 10,535 and 35,475 person-seasons from vaccinated and unvaccinated individuals, respectively. The mean proportion of individuals vaccinated per season was 23% (range 19-25%). VE estimates for individual seasons ranged from -74 to 66% for influenza and -58 to 29% for influenza-like infection, and were similar in immunosuppressed patients and those with diabetes. In the pooled analysis comparing matched vs. mismatched seasons, vaccination was modestly protective for both influenza (VE 17%, 95% CI -38 to 50) and influenza-like infection (VE 14%, 95% CI -24 to 41%), though estimates were limited by sample size.
CONCLUSION: Rates of influenza vaccination are suboptimal among patients with GD. Despite potential confounding by indication and uncaptured vaccinations and infections, these data suggest that protection from influenza after vaccination may be poor, leading to excess infection-related morbidity in this vulnerable population.
