Impact of vitamin D levels on mortality in older covid-19 vaccinated patients

Background: Vitamin D plays a key role in regulating the immune system and vaccine response, and hypovitaminosis D is a known risk factor for mortality. However, its potential influence on mortality in SARS-CoV-2 vaccinated older adults remains underexplored. This study aims to examine survival differences between unvaccinated and vaccinated older adults with varying vitamin D levels, and to assess the impact of vitamin D on mortality. Methods: We recruited patients aged 65 and over from the Geriatrics Unit of Azienda Ospedale - Università Padova. Clinical, pharmacological data, including vaccination status and vitamin D levels, were collected at admission, alongside mortality data 12 months post-hospitalization. Participants were divided into three groups: unvaccinated, vaccinated with vitamin D levels of 25–50 nmol/L, and vaccinated with levels > 50 nmol/L. Results: A total of 126 participants were included (56% women, mean age 83 years). No significant differences were found in COVID-19 severity among the three groups. After 12 months, 24 deaths were recorded: 17% in unvaccinated, 19% in vaccinated with low vitamin D, and 20% in vaccinated with high vitamin D (p = 0.94). Kaplan-Meier curves showed that mortality risk for vaccinated individuals with low vitamin D was similar to unvaccinated patients but significantly higher than vaccinated individuals with high vitamin D (p = 0.04). Vitamin D levels of 25–50 nmol/L were associated with a threefold increased risk of 12-month mortality (HR: 3.79, p < 0.001). Conclusions: Vitamin D levels can impact mortality in older vaccinated individuals. Early correction of vitamin D deficiency could potentially enhance outcomes.