Vitamin D and COVID-19 Research


There is evidence that vitamin D may prevent or improve outcomes in many infectious and inflammatory conditions including acute and chronic respiratory infections. There is also an increasing understanding of its immunomodulatory and anti-inflammatory functions. A recent meta-analysis found a 70% reduction in viral respiratory tract infections among persons with vitamin D deficiency randomized to vitamin D treatment.

The potential importance of vitamin D in the spread of COVID in the U.S. is supported by the fact that nearly half of the population is vitamin D deficient, with higher rates among persons with darker skin and/or lower sun exposure, including those living in higher latitudes in the winter, nursing home residents, and health care workers, who also have greater risk of COVID-19.1,2,3,4,5 Using data from the University of Chicago Medical Center, we provided some of the earliest evidence to support the hypothesis that vitamin D deficiency may affect COVID-19 risk, finding that patients with vitamin D deficiency that was not adequately treated were 77% more likely to test positive for COVID-19 than patients who were not likely vitamin D deficient.6,7 Several other observational analyses are in progress and will be reported on this website as they become available.

Vitamin D Intervention Studies

Because associations observed in observational studies may not necessarily reflect a causal relationship, a team of researchers in CHeSS, the Section of Hospital Medicine, and the Urban Health Lab at the University of Chicago led by Dr. David Meltzer are conducting several clinical intervention studies to examine whether vitamin D treatment can aid in the prevention of COVID-19 infection or reduce the severity of infection among different groups of people. These studies are ongoing and are described below.

Moderate or High-Dose Vitamin D Supplementation

This one-year study, funded by the National Institute of Health (NIH) National Center for Advancing Translational Science (NCATS), is a double-blinded randomized controlled trial in which participants select a maximum vitamin D dose to which they might be randomized that is either moderate (4,000 IU) or high (10,000 IU), and are then randomized between that preferred moderate or high dose and a low dose of 400 IU, which serves as the control group. Originally planned to recruit 2,000 health care workers, we have broadened this study to also include persons who are not health care workers as many health care workers gained early access to vaccination, which is expected to decrease their risk of infection. All subjects receive quarterly surveys to ask about their health and behaviors, and visit the lab at the University of Chicago Medical Center, Rush University Medical Center, or Ingalls Hospital for blood tests to monitor their calcium and vitamin D levels and COVID-19 antibodies. Subjects receive COVID-19 testing, if necessary, through their usual sources of care. To learn more about this study, click here.

Vitamin D Supplementation in United States Communities

This randomized controlled trial seeks to understand whether vitamin D supplementation (4,000IU vs. 400IU, serving as the control) can reduce incidence and adverse health outcomes of COVID-19 in a diverse cross-section of United States communities, especially Black and Hispanic/Latinx individuals and communities more affected by adverse outcomes of infection. The plan is to recruit about 2,000 individuals who will participate the study for 12 months. In addition to receiving vitamin D, subjects will receive and be asked to complete quarterly web surveys about their health, behaviors, and COVID-19 exposure, and can opt-in to antibody testing at the conclusion of the study. To learn more about this study, click here.

Vitamin D Treatment in the Comprehensive Care Program Studies

This one-year observational study, housed within ongoing randomized trials evaluating our Comprehensive Care Physician (CCP) and Comprehensive Care, Community & Culture Program (C4P) studies at the University of Chicago, tests whether vitamin D levels and supplementation based on levels affect COVID-19 incidence and outcomes. The study population includes adults at increased risk of hospitalization with complex medical and social needs. Study participants will complete vitamin D tests quarterly and receive recommendations from their Comprehensive Care Physician about vitamin D dosing based on their measured levels and targets for their treatment. Surveys will be completed quarterly to assess for COVID-19 exposure, sun exposure, behaviors, and diet. To learn more about this study, click here.


Meltzer DO, Best TJ, Zhang H, Vokes T, Arora VA, Solway J. Association of Vitamin D Status and Other Clinical Characteristics with COVID-19 Test Results. JAMA. 2020; 3(9):e2019722. Read the article | Listen to JN Learning interviewView article Altmetrics.

Meltzer DO, Best TJ, Zhang H, Vokes T, Arora VM, Solway J. Association of Vitamin D Levels, Race/Ethnicity, and Clinical Characteristics With COVID-19 Test Results. JAMA Netw Open. 2021;4(3):e214117. Read the article | Read UChicago Press Release | View article Altmetrics.  

Vitamin D in the News

April 14, 2021 – Dr. Meltzer discusses the link between vitamin D and COVID-19 on WBEZ Chicago. Read the WBEZ report here.

April 9, 2021 – Watch Dr. Meltzer and Dr. Raphael Lee answer questions about the potential health benefits of vitamin D and discuss a new study to learn if taking a daily vitamin D supplement can help prevent COVID-19 or decrease the severity of its symptoms. Watch the Facebook Live event here.

February 28, 2021 – ABC 7 in Chicago features current research on whether vitamin D supplements can reduce the risk and severity of COVID-19. Watch here.

September 30, 2020 – Dr. Meltzer discusses vitamin D and COVID-19 on The Doctors tv show.  Watch here. 

September 8, 2020 – University of Chicago press release features JAMA study on vitamin D. Read here.

September 3, 2020 – Vitamin D research is highlighted by the Chicago Tribune and local news outlets. Tribune article. NBC ChicagoABC Chicago.

June 10, 2020 – Dr. Meltzer is cited in a New York Times article discussing the potential  links between vitamin D and COVID-19. NYTimes article.

View Altmetric data, which includes a comprehensive list of media mentions, here