Vitamin D Status and Incidence of SARS-CoV-2 Reinfections in the Borriana COVID-19 Cohort: A Population-Based Prospective Cohort Study

A deficient vitamin D (VitD) status has been associated with SARS-CoV-2 infections, severity, and mortality. However, this status related to SARS-CoV-2 reinfections has been little studied. Our aim was to quantify the risk of reinfections considering VitD status before reinfection. Methods: We performed a population-based prospective cohort study in Borriana (Valencia Community, Spain) during 2020-2023 years, measuring 25-hydroxyvitamin D [25(OH)D] levels by electrochemiluminescence. Cox proportional hazards models were employed. Results: Of a total of 644 SARS-CoV-2 cases with confirmed laboratory tests, 378 (58.9%) were included in out study with an average age of 38.8 years, 241 were females (63.8%), and 127 reinfections occurred (33.6%). SARS-CoV-2 reinfection incidence rates per 1000 person-days by VitD status were for a deficient status 0.4983 (< 20 ng/ml), 0.4977 for insufficient (20-29 ng/ml), and 0.3713 for sufficient (≥30ng/ml). Compared with sufficient VitD status, adjusted hazard ratios were 1.79 (95% Confidence Interval [CI] 0.89-3.59) for deficient status and 1.59 (95% CI 1.06-2.38) for insufficient status with a significant inverse dose-response (p=0.02). These results can help improve nutritional actions against SARS-CoV-2 reinfections. Conclusions: These results suggest that a VitD status lower than 30 ng/ml showed a higher risk of SARS-CoV-2 reinfection. Achieving and maintaining a sufficient VitD status is recommended to prevent reinfections.