COVID-19NCT07128069
Can Vitamin D Reduce the Burden of COVID-19?
A study testing Vitamin D 400IU and Vitamin D 4000IU in people with COVID-19, run by University of Chicago at 1 site in United States.
Trial summary
The purpose of this study is to compare the risks of COVID-19 in individuals from the Chicagoland area and other communities in the United States randomized to low (400 IU/day) versus moderate (4,000 IU/day) dose vitamin D. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- COVID-19
- What is being tested?
- Vitamin D 400IU and Vitamin D 4000IU
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 2,093 participants
- Where
- 1 siteUnited States
- Study dates
- 28 Dec 2020to 9 Dec 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Subjects are able to participate if they:
- Are 18 years or older.
- Live in the United States.
- Are interested in vitamin D as a potential preventive measure against COVID-19 in which they self-administer a daily dose of vitamin D during the 12-month study period.
- Are willing to complete self-report measures at 5 time points over the course of 12 months by completing a 15-minute survey at intake via web and 10-minute web-based follow-up surveys.
Who cannot join
- Subjects are excluded from study participation if they:
- Report being pregnant, planning to become pregnant, and/or report breastfeeding during the study period.
- Report a history of chronic kidney disease, including a history of abnormal GFR and/or creatinine.
- Report a history of hyperparathyroidism.
- Report a history of increased falls.
- Report a history of hypercalcemia.
Show all 11Show fewer
- Report a history of gastrointestinal absorptive disorders, including having undergone bariatric surgery.
- Report a history of kidney stones (1 in past year or 2 in lifetime).
- Report already taking more than 400 IU of vitamin D daily as recommended by their health care provider, excluding multivitamins and excluding supplements that include vitamin D and calcium together.
- Report taking D2.
- Report a history of sarcoidosis.
Trial locations and contacts
1 site in 1 country.
About this study
The purpose of this study is to compare the risks of COVID-19 in individuals from the Chicagoland area and other communities in the United States randomized to low (400 IU/day) versus moderate (4,000 IU/day) dose vitamin D.
Read the detailed description
This study will recruit 2,000 subjects from the Chicagoland area and across the United States to participate in the study from home. Subjects will be invited to volunteer to participate in the study through a variety of forms of outreach, mainly online (e.g., press releases, news interviews, social media, emails, etc.). The sample size was chosen to have at least 80% power to detect a 20% or larger decrease in the hazard of developing COVID-19 between study arms at p<0.05, based on an estimated monthly incidence of COVID-19 (3%/month for Black/Latinx persons and 1%/month for White persons) and an estimated fraction of persons already immune but unaware they have had COVID-19 (≤10%).
Subjects will take a daily dose of vitamin D and answer surveys about COVID-19 diagnosis and symptoms over 12 months after enrollment.
Our overall aim is to compare the risks of COVID-19 in adults at increased risk of COVID-19 randomized to low (400 IU/day) versus moderate (4,000 IU/day) dose vitamin D. Our specific aims are:
Aim 1: To compare the risk of developing COVID-19 in adults at increased risk of COVID-19 randomized to low versus moderate dose vitamin D. We hypothesize that moderate dose therapy will reduce rates of COVID-19 compared to low dose therapy because vitamin D will reduce symptomatic infection that prompts testing for COVID-19.
Aim 2: To compare COVID-19 outcomes (symptoms, hospitalization, ICU stay, ventilator use, death) in adults at increased risk of COVID-19 randomized to low vs. moderate dose vitamin D. Consistent with several recent observational analyses, we expect higher doses to improve COVID-19 outcomes.
Subjects will be asked to complete a web-based survey at intake and at 3, 6, 9, and 12 months after enrollment. The intake survey will collect baseline data on subjects' current medications and supplements, sun exposure, exercise, diet and sleep habits, possible COVID-19 symptoms, other influenza-like symptoms, previous exposures to COVID-19, occupation, demographic information, and risks of exposure. The surveys at 3, 6, 9, and 12 months after enrollment will ask the participant or a proxy whether the participant has had a clinically confirmed diagnosis of COVID-19 and the date if so, ask about rates of study medication adherence, and assess for changes in the intake questions about use of other supplements, sun exposure, diet, exercise, and COVID-19 exposures. If the subject reports to have had COVID-19, we will ask about severity, including symptoms, hospitalization and duration, ICU use and duration, need for mechanical ventilation and duration, and death.
- Conditions
- COVID-19
- Being tested
- Vitamin D 400IU, Vitamin D 4000IU
- Keywords
- vitamin D
- Medical subject headings
- COVID-19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Vitamin D 400IUDietary supplement
Also called Vitamin D3
Low dose vitamin D (400 IU/day)
Vitamin D 4000IUDietary supplement
Also called Vitamin D3
Moderate dose vitamin D (4000 IU/day)
| Study group | Role | What they receive |
|---|---|---|
| Low Dose Vitamin D (400 IU/day) | Active comparator | Subjects in this arm will be randomized to receive low dose vitamin D (oral, 400 IU/day) for 12 continuous months Receives: Dietary Supplement: Vitamin D 400IU |
| Moderate Dose Vitamin D (4000 IU/day) | Active comparator | Subjects in this arm will be randomized to receive moderate dose vitamin D (oral, 4000 IU/day) for 12 continuous months Receives: Dietary Supplement: Vitamin D 4000IU |
What is being measured
The primary outcome is the main question the study is designed to answer.
Time from randomization to first participant-reported COVID-19 infection
Reported in a post-randomization survey
Measured: From date of randomization to the earliest of either the first participant-reported COVID-19 infection up to and including 365 days after randomization or right censoring up to 365 days after randomization
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Aug 2025
- Study start28 Dec 2020
- Primary completion15 Feb 2025
- Study completion9 Dec 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for COVID-19Studies of the same condition, open and under way.
- More trials run by University of ChicagoThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- 2,000-person two-arm, double-blinded randomized controlled trial, with half the subjects randomized to low dose vitamin D (400 IU/day), which will serve as the control group, and half to moderate dose vitamin D (4,000 IU/day)
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 2,093 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Chicago
- Sponsor type
- University, hospital or other
- Collaborators
- Cures Within Reach
- Responsible party
- Sponsor
- Investigators
- David O Meltzer, MD, PhD, Study director, University of Chicago
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07128069
- Sponsor's protocol ID
- IRB20-0847
- Status last verified
- Aug 2026
- First submitted
- 15 Aug 2025
- Last updated
- 7 Aug 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Individual participant data underlying the text, tables, figures, and appendices of article publications will be made available after deidentification. We will also provide the study protocol and statistical analysis plan. Data will be available six months after article publication until five years following article publication. Researchers wishing to use the data must prepare a protocol for the use of the data which will be reviewed for methodological soundness and potential human subjects concerns by the study investigators and the UChicago Medicine Institutional Review Board. Individual participant meta-analysis and other purposes will be considered. Proposals should be directed to dmeltzer@bsd.uchicago.edu. To gain access, data requestors will need to complete a data access agreement. Data will be accessible through a secure website.
Study at a glance
From the registry record, last updated by the sponsor on 7 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Can Vitamin D Reduce the Burden of COVID-19?
- ClinicalTrials.gov ID
- NCT07128069
- Acronym / sponsor ID
- IRB20-0847
- Conditions
- COVID-19
- Keywords
- vitamin D
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 2,093 participants (actual)
- Lead sponsor
- University of ChicagoUniversity, hospital or other
- Collaborators
- Cures Within Reach
- Study start
- 28 Dec 2020 (actual)
- Primary completion
- 15 Feb 2025 (actual)
- Study completion
- 9 Dec 2025 (actual)
- First posted
- 17 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The purpose of this study is to compare the risks of COVID-19 in individuals from the Chicagoland area and other communities in the United States randomized to low (400 IU/day) versus moderate (4,000 IU/day) dose vitamin D.
Detailed description
This study will recruit 2,000 subjects from the Chicagoland area and across the United States to participate in the study from home. Subjects will be invited to volunteer to participate in the study through a variety of forms of outreach, mainly online (e.g., press releases, news interviews, social media, emails, etc.). The sample size was chosen to have at least 80% power to detect a 20% or larger decrease in the hazard of developing COVID-19 between study arms at p<0.05, based on an estimated monthly incidence of COVID-19 (3%/month for Black/Latinx persons and 1%/month for White persons) and an estimated fraction of persons already immune but unaware they have had COVID-19 (≤10%).
Subjects will take a daily dose of vitamin D and answer surveys about COVID-19 diagnosis and symptoms over 12 months after enrollment.
Our overall aim is to compare the risks of COVID-19 in adults at increased risk of COVID-19 randomized to low (400 IU/day) versus moderate (4,000 IU/day) dose vitamin D. Our specific aims are:
Aim 1: To compare the risk of developing COVID-19 in adults at increased risk of COVID-19 randomized to low versus moderate dose vitamin D. We hypothesize that moderate dose therapy will reduce rates of COVID-19 compared to low dose therapy because vitamin D will reduce symptomatic infection that prompts testing for COVID-19.
Aim 2: To compare COVID-19 outcomes (symptoms, hospitalization, ICU stay, ventilator use, death) in adults at increased risk of COVID-19 randomized to low vs. moderate dose vitamin D. Consistent with several recent observational analyses, we expect higher doses to improve COVID-19 outcomes.
Subjects will be asked to complete a web-based survey at intake and at 3, 6, 9, and 12 months after enrollment. The intake survey will collect baseline data on subjects' current medications and supplements, sun exposure, exercise, diet and sleep habits, possible COVID-19 symptoms, other influenza-like symptoms, previous exposures to COVID-19, occupation, demographic information, and risks of exposure. The surveys at 3, 6, 9, and 12 months after enrollment will ask the participant or a proxy whether the participant has had a clinically confirmed diagnosis of COVID-19 and the date if so, ask about rates of study medication adherence, and assess for changes in the intake questions about use of other supplements, sun exposure, diet, exercise, and COVID-19 exposures. If the subject reports to have had COVID-19, we will ask about severity, including symptoms, hospitalization and duration, ICU use and duration, need for mechanical ventilation and duration, and death.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- 2,000-person two-arm, double-blinded randomized controlled trial, with half the subjects randomized to low dose vitamin D (400 IU/day), which will serve as the control group, and half to moderate dose vitamin D (4,000 IU/day)
| Arm | Type | Receives |
|---|---|---|
| Low Dose Vitamin D (400 IU/day) | Active comparator | Dietary Supplement: Vitamin D 400IUSubjects in this arm will be randomized to receive low dose vitamin D (oral, 400 IU/day) for 12 continuous months |
| Moderate Dose Vitamin D (4000 IU/day) | Active comparator | Dietary Supplement: Vitamin D 4000IUSubjects in this arm will be randomized to receive moderate dose vitamin D (oral, 4000 IU/day) for 12 continuous months |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Are 18 years or older.
- Live in the United States.
- Are interested in vitamin D as a potential preventive measure against COVID-19 in which they self-administer a daily dose of vitamin D during the 12-month study period.
- Are willing to complete self-report measures at 5 time points over the course of 12 months by completing a 15-minute survey at intake via web and 10-minute web-based follow-up surveys.
Key exclusion criteria (11 listed)
- Report being pregnant, planning to become pregnant, and/or report breastfeeding during the study period.
- Report a history of chronic kidney disease, including a history of abnormal GFR and/or creatinine.
- Report a history of hyperparathyroidism.
- Report a history of increased falls.
- Report a history of hypercalcemia.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Vitamin D 400IUAlso: Vitamin D3Low dose vitamin D (400 IU/day) | Dietary supplement | Low Dose Vitamin D (400 IU/day) |
| Vitamin D 4000IUAlso: Vitamin D3Moderate dose vitamin D (4000 IU/day) | Dietary supplement | Moderate Dose Vitamin D (4000 IU/day) |
Primary outcome
Time from randomization to first participant-reported COVID-19 infection
Time frame: From date of randomization to the earliest of either the first participant-reported COVID-19 infection up to and including 365 days after randomization or right censoring up to 365 days after randomization
Reported in a post-randomization survey
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Aug 2026.
- Individual participant dataSharing planned: Yes. Individual participant data underlying the text, tables, figures, and appendices of article publications will be made available after deidentification. We will also provide the study protocol and statistical analysis plan. Data will be available six months after article publication until five years following article publication. Researchers wishing to use the data must prepare a protocol for the use of the data which will be reviewed for methodological soundness and potential human subjects concerns by the study investigators and the UChicago Medicine Institutional Review Board. Individual participant meta-analysis and other purposes will be considered. Proposals should be directed to dmeltzer@bsd.uchicago.edu. To gain access, data requestors will need to complete a data access agreement. Data will be accessible through a secure website.
Related trials for COVID-19
Not yet recruitingPhase 1
Phase I Open-Label Safety Trial of Pembrolizumab for Neurological Post- Acute Sequelae of SARS-CoV-2 (PD1-PASC I)
Post-Acute COVID-19 Syndrome
Active, not recruitingPhase 1
A Safety and Immunogenicity Trial of OCU500, ChAd36 Vector Encoding SARS-CoV-2 Spike Vaccine Via Intranasal and Inhalational Routes in Previously Vaccinated Adults
COVID-19
Active, not recruiting
Intervention to Address Disparate Mental Health Consequences of COVID-19 Pandemic on Latinx and African Newcomers
Mental Health Issue, Mental Health Disorder
Recruiting
Home-Based Exercise Tele-Rehabilitation After COVID-19
Post SARS-CoV2 (COVID-19)
Not yet recruitingPhase 1
A Safety, Reactogenicity and Immunogenicity Trial of RVX-sCPD9 Booster Intranasal COVID-19 Vaccine
COVID -19
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
David O Meltzer, MD, PhD study director
University of Chicago
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Vitamin D 400IU and Vitamin D 4000IU in people with COVID-19, run by University of Chicago at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 7 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Time from randomization to first participant-reported COVID-19 infection (time frame: From date of randomization to the earliest of either the first participant-reported COVID-19 infection up to and including 365 days after randomization or right censoring up to 365 days after randomization). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Aug 2026.