An Israeli study concluded that over 26% of vitamin D deficient patients hospitalized for Covid-19 died, compared to under 3% of non-deficient patients.
Because of Israel’s centralized medical record-keeping, the study was able to access and utilize patient vitamin D levels from prior to hospitalization, helping to judge if levels were predictive of outcome.
Of 1176 individuals admitted for COVID-19 at the Galilee Medical Center between April 7th, 2020, and February 4th, 2021, historical VitD levels were obtained between 14 and 730 days before the first positive COVID-19 test for 253 (21.5%) individuals (mean age 63.3 [SD=18.6] years; 144 [56.9%] women). Of the 253 individuals with pre-infection VitD levels, 133 (52.5%) had a level less than 20 ng/mL, 36 (14.2%) had 20 to less than 30 ng/mL, 44 (17.3%) had 30 to less than 40 ng/mL, and 40 (15.8%) had 40 ng/mL or greater. Mortality among patients with sufficient VitD levels was 2.3%, in contrast to the VitD deficient group’s 25.6% mortality rate (p-value<0.001). Stratified by COVID-19 disease severity, lower vitamin D levels were more common in patients with severe or critical disease (<20 ng/mL: 76 of 87 individuals [87.4%]) than individuals with mild or moderate disease (<20 ng/mL: 57 of 166 individuals [34.3%] p-value<.001).
These results shouldn’t be surprising. The connection between susceptibility to respiratory infection and low vitamin D has been know for many years, and demonstrated by previous studies, as explained by this study’s authors:
[C]linical studies have established an association between low vitamin D levels and an increased risk of acquiring influenza and respiratory viruses. Meta-analyses of randomized controlled trials conducted between 2007 and 2020 suggest that vitamin D supplementation was safe and reduced the risk of acute respiratory infection compared with placebo.