Older adults get renoprotection from flu vaccine

Influenza vaccination appears to provide a protective benefit against acute kidney injury (AKI) in older adults, according to a study.

Analysis of large data from the UK Biobank showed that the primary outcome of AKI incidence over 1 year after vaccination was lower relative to nonreceipt of the vaccine, at 30.6 vs 36.8 per 10,000 person-years. Influenza vaccination was associated with a 17-percent reduction in the risk of AKI (hazard ratio [HR], 0.83, 95 percent confidence interval [CI], 0.71–0.98). [Am J Kidney Dis 2025;doi:10.1053/j.ajkd.2025.09.005]

Additionally, cumulative mortality rates decreased from 62.8 to 47.2 per 10,000 person-years following influenza vaccination, corresponding to a 25-percent risk reduction (HR, 0.75, 95 percent CI, 0.66–0.85).

The observed benefits remained consistent across subgroup and sensitivity analyses.

These findings align with growing evidence suggesting that influenza vaccination may have a broader renal protective role beyond preventing respiratory complications, the authors said, adding that the vaccine likely protects the kidneys by dampening the body’s inflammatory overreaction to the virus.

“[Vaccination mitigates] the severity of influenza infection, thereby reducing the likelihood of cytokine storms and hemodynamic instability—both known precursors of AKI,” the authors noted. [PLoS Pathog 2021;17:e1009928; Theranostics 2021;11:316-329]

Another possibility is that vaccination prevents influenza-induced kidney injury, which is induced by various factors such as acute tubular necrosis due to kidney hypoperfusion, rhabdomyolysis, or glomerular microthrombosis caused by disseminated intravascular coagulation. [Eur J Pediatr 2013;172:15-22]

“Our medication analysis result supports reducing influenza or pneumonia as a potential mechanism of AKI protection, but further in-depth investigations into the underlying mechanisms are warranted,” the authors said.

“On the other hand, the sporadic case reports of AKI following vaccination highlight the complexity of immune-mediated renal insults, suggesting that individuals with pre-existing autoimmune conditions or kidney vulnerabilities may be at increased risk,” they continued. [Vaccines (Basel) 2023;11:1098]

Additional research are needed to replicate the present data in various populations and clinical settings in order to establish whether influenza vaccination truly confers a renoprotective effect, they added.

The current study included 1,408,922 eligible person-trials in general practice, with 98,003 older adults receiving influenza vaccination. They constructed a propensity-score matched cohort including 97,663 pairs of vaccinated and unvaccinated person-trials (mean age 69.2 years, 47 percent male, mean BMI 27.6 kg/m²).

The authors acknowledged that the study was limited by potential residual confounding from variations in vaccine formulations and batch, potential selection bias from restricting to participants with linked primary care data in the UK Biobank, and potential outcome misclassification from use of a code-based algorithm to identify AKI.