Low Vitamin D Levels Are Associated With Long COVID Syndrome in COVID-19 Survivors

Abstract Context Long COVID is an emerging syndrome affecting 50% to 70% of COVID-19 survivors that still lacks predicting factors. Objective Due to the extraskeletal effects of vitamin D, we retrospectively assessed the association between 25(OH) vitamin D levels and long COVID in COVID-19 survivors 6 months after hospitalization. Methods Long COVID was defined according to NICE guidelines. Fifty long COVID and 50 non–long-COVID subjects matched on a 1:1 basis were enrolled from an outpatient clinic post-COVID cohort seen from August to November 2020. Therapies/comorbidities affecting calcium/vitamin D/bone metabolism, and/or admission to the intensive care unit during hospitalization were exclusion criteria. 25(OH) Vitamin D was measured at hospital admission and 6 months after discharge. Results We observed lower 25(OH) vitamin D levels, evaluated at follow-up, in subjects with long COVID than those without (20.1 vs 23.2 ng/mL, P = .03). Regarding the affected health areas evaluated in the entire cohort, we observed lower 25(OH) vitamin D levels in those with neurocognitive symptoms at follow-up (n = 7) than those without (n = 93) (14.6 vs 20.6 ng/mL, P = .042). In patients presenting vitamin D deficiency (