Retrospective study of 107 COVID-19 patients with vitamin D levels measured within 180 days before diagnosis, and 203 patients with levels measured after diagnosis, showing lower vitamin D levels for COVID-19 hospitalized patients compared to non-COVID-19 patients, but no significant association between vitamin D levels before infection and cases. Authors do not analyze the risk of serious outcomes based on pre-infection levels. Results are provided only for vitamin D as a continuous variable.
Gupta et al., 7/2/2022, USA, peer-reviewed, 4 authors, study period 1 January, 2020 - 30 September, 2020.
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