VITAMIN D deficiency remains significantly associated with worse clinical outcomes in patients with COVID-19, even in the post-Omicron era, according to new findings from a large-scale retrospective cohort study.
The study evaluated over 46,000 matched patients using the TriNetX Analytics Network to compare the effects of vitamin D deficiency (VDD, defined as serum 25-hydroxyvitamin D <20 ng/ml) on COVID-19 outcomes in both the pre- and post-Omicron pandemic phases. Patients with vitamin D levels ≥30 ng/ml served as the comparison group. In the post-Omicron phase (June 2022 to December 2023), all-cause 30-day mortality was higher among VDD patients compared to vitamin D–sufficient counterparts: 0.89% vs. 0.49%, respectively (odds ratio [OR], 1.82; 95% CI, 1.46–2.28; p < 0.001). Though this association was attenuated from the pre-Omicron phase, where the OR was 3.67, the findings confirm VDD as an ongoing contributor to adverse outcomes. Similar patterns of risk reduction but persistence were observed for other complications. For example, acute kidney injury risk declined from an OR of 2.11 pre-Omicron to 1.41 post-Omicron, while respiratory failure and pneumonia risks also decreased but remained elevated for VDD patients. The study further identified significant predictors of mortality in VDD individuals during the post-Omicron phase, including malnutrition (OR, 4.34), liver disease (OR, 3.08), and malignancies (OR, 2.63). Researchers suggest that although the clinical severity of COVID-19 has diminished in the post-Omicron era, vitamin D deficiency continues to impact outcomes. These results underscore the relevance of maintaining adequate vitamin D levels and call for targeted screening in high-risk populations, particularly those with additional comorbidities. The authors advocate for adaptive risk stratification approaches that integrate both historical and newly emerging risk factors, as the clinical profile of COVID-19 continues to evolve. Reference: Chen I-W et al. Association between vitamin D deficiency and clinical outcome in patients with COVID-19 in the post-Omicron phase. Front Nutr. 2025:12:1583276.
