Deficient vitamin D status associated with increased COVID-19 risk

Researchers from a retrospective study have reported an association between vitamin D deficiency and an increase in the risk of becoming infected with the coronavirus.

The findings were reported on Sept. 3, 2020 in JAMA Network Open.

“Vitamin D is important to the function of the immune system and vitamin D supplements have previously been shown to lower the risk of viral respiratory tract infections,” said author David Meltzer, MD, PhD, Chief of Hospital Medicine at the University of Chicago Medical Center. “Our statistical analysis suggests this may be true for the COVID-19 infection.”

As background, Meltzer said, “Understanding whether treating Vitamin D deficiency changes COVID-19 risk could be of great importance locally, nationally and globally,” Meltzer said. “Vitamin D is inexpensive, generally very safe to take, and can be widely scaled.”

For this retrospective study, the investigators included data on patients with a 25-hydroxycholecalciferol or 1,25-dihydroxycholecalciferol level measured within 1 year before being tested for COVID-19 (from March 3 to April 10, 2020.)

They defined vitamin D deficiency by the last measurement of 25-hydroxycholecalciferol less than 20 ng/mL or 1,25-dihydroxycholecalciferol less than 18 pg/mL before COVID-19 testing.

“Vitamin D deficiency and treatment changes were combined to categorize the most recent vitamin D status before COVID-19 testing as likely deficient (last level deficient and treatment not increased), likely sufficient (last level not deficient and treatment not decreased), and 2 groups with uncertain deficiency (last level deficient and treatment increased, and last level not deficient and treatment decreased),” the authors said.

The primary outcome was a positive COVID-19 test result and whether vitamin D status before COVID-19 testing was subsequently associated with testing positive for COVID-19. All subjects had their vitamin D level measured in the year before COVID-19 testing.

The investigators gathered and analyzed data on489 subjects (mean age 49.2 years 366 females and 331 non-White)

Vitamin D status before COVID-19 testing was: “likely deficient” for 124 subjects (25%), “likely sufficient” for 287 (59%) and “uncertain” for 78 (16%).

Of the total study cohort, 71 subjects (15%) tested positive for COVID-19.

Predicted COVID-19 rates in the vitamin D deficient group were 21.6%, and 12.2% in the vitamin D sufficient group.

The authors concluded, “In this single-center, retrospective cohort study, likely deficient vitamin D status was associated with increased COVID-19 risk, a finding that suggests that randomized trials may be needed to determine whether vitamin D affects COVID-19 risk.”