Skip to content

Low vs. Moderate to High Dose Vitamin D for Prevention of COVID-19

Low vs. Moderate to High Dose Vitamin D for Prevention of COVID-19

Status
Completed
Phases
Unknown
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04868903
Enrollment
1475
Registered
2021-05-03
Start date
2020-11-30
Completion date
2024-12-01
Last updated
2026-07-22

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

SARS-CoV-2 Infection

Brief summary

The purpose of this study is to compare the risks of COVID-19 in individuals from Chicagoland communities randomized to low (400 IU/day) vs. moderate (4,000 IU/day) or high (10,000 IU/day) dose vitamin D.

Detailed description

This study will recruit 2,000 subjects from the Chicagoland area to participate in the study at University of Chicago Medicine (UCM) and at Rush University (RU). Subjects will be invited to volunteer to participate in the study through a variety of forms of community outreach (flyers, presentations, emails, etc.). The sample size was chosen to have at least 80% power to detect a 25% or larger decrease in the hazard of developing COVID-19 between study arms at p\<0.05 assuming a 30% baseline COVID-19 incidence rate over the study period, in line with a 3% per month incidence. Subjects will take a daily dose of vitamin D, attend laboratory appointments for testing, and answer surveys over 9 months after enrollment. Our overall aim is to compare the risks of COVID-19 in adults in the Chicagoland area at increased risk of COVID-19 randomized to low (400 IU/day) vs. moderate (4,000 IU/day) or high (10,000 IU/day) dose vitamin D. Our specific aims are: Aim 1: To compare the risk of developing COVID-19 in adults in the Chicagoland area at increased risk of COVID-19 randomized to low vs. moderate or high dose vitamin D. Subjects will specify their preference for moderate versus high dose vitamin D and then be randomized between low dose vitamin D and their preferred moderate or high dose alternative. We hypothesize that moderate and high 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. Our primary analysis will pool subjects randomized to the moderate or high dose and compare them to low dose subjects, with secondary analyses comparing low to moderate and low to high. Aim 2: To compare COVID-19 seroconversion in adults in the Chicagoland area at increased risk of COVID-19 randomized to low vs. moderate or high dose vitamin D. As we suspect the main effect of vitamin D may be to decrease symptomatic disease we hypothesize that there may be little or no difference in seroconversion. Aim 3: To compare COVID-19 outcomes (hospitalization, ICU stay, ventilator use, death) in adults in the Chicagoland area at increased risk of COVID-19 randomized to low vs. moderate or high dose vitamin D. Consistent with several recent observational analyses, we expect higher doses to improve COVID-19 outcomes. Additional aims examine the relationship between vitamin D and other markers of immune response: Aim 4: Create a biobank of PBMCs from a panel of 500 individuals with well characterized levels of vitamin A and D. We propose to cryopreserve PBMCs derived from \ 20 ml of blood to test the impact of vitamin A and D levels in the regulation of immune responses. Aim 5: Evaluate the impact of vitamin A and D levels on immune function. We will perform immunophenotyping of PBMC using a panel of 30 antibodies that allow characterizing the different immune cell populations found in circulation, as well as their functional status. Using these data we will ask if there is an association between the prevalence of certain immune cell population or functional potential and vitamin A and D levels. Aim 6: Evaluate the impact of vitamin A and D levels on PBMC gene expression levels. We will perform transcriptional profiling of PBMC from a panel of 100 individuals enriched for individuals on the two extremes of the distributions of vitamin A and D levels. These data will be used to identify changes in gene expression levels that differ between individuals showing low- vs high-vitamin A/D levels. Aim 7: To test the hypothesis that oral vitamin D3 intervention will inhibit the renin- angiotensin system and reduce the incidence and/or severity of COVID-19 infections Blood labs will be taken from subjects at intake, 3 months, 6 months and 9 months. Intake labs will measure baseline calcium and PTH levels, COVID-19 antibodies, and vitamin D. Intake labs for a subset of University of Chicago Medicine (UCM) subjects will additionally measure vitamin A, vitamin D-binding protein (DBP), RAS components (Renin, Ang II, soluble ACE and ACE2), bradykinin, inflammation markers (IL-6, TNF-a, IL-1b and CRP), and SARS-CoV-2 antibodies against S-protein and N-protein. 3-month labs for all subjects will measure PTH, calcium, and vitamin D for monitoring of the intervention's safety and outcomes, and COVID-19 antibodies for monitoring of the outcome. 6-month and 9-month labs for all subjects will measure PTH, calcium, and vitamin D for monitoring of the intervention's safety and COVID-19 antibodies for monitoring of the outcome. Vitamin A will be measured for a subset of UCM subjects who were high at baseline. Throughout the study period we will tell subjects about calcium, PTH and vitamin D lab results only if they suggest a safety concern for which we would like them to seek care. Subjects will be told if they test positive for COVID-19 antibodies. Except in the instance of a safety concern, subjects will be blinded to their vitamin A & D levels, calcium and PTH throughout the study to ensure protocol compliance. At the end of the study, we will inform subjects of their vitamin D levels. Electronic Medical Records will be reviewed for predictors and indicators of COVID-19 and for severity of infection if subject has had a positive COVID-19 test result. Subjects will be asked to complete a web-based survey at intake, 3, 6 and 9 months. The intake survey will collect baseline data on subjects' current medications and supplements, sun exposure, Fitzpatrick skin type, exercise, diet and sleep habits, possible COVID-19 symptoms, and other influenza-like symptoms. Subjects will also be asked to report suspected exposure to the virus, occupation, and demographic information. Subjects will also be asked to evaluate risks of exposure. Follow-up surveys at months 3, 6, and 9 will ask the participant (or 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 patient is reported to have had COVID-19, we ask about severity, including hospitalization and duration, ICU-use and duration, and need for mechanical ventilation and duration, death and COVID-19 symptom severity.

Interventions

DIETARY_SUPPLEMENTVitamin D3

Half the subjects will be randomized to the low dose vitamin D therapy (400 IU/day), which will serve as the control group, and half to moderate (4,000 IU/day) or high (10,000 IU/day). Study participants will have the option between being randomized to the low versus moderate or the low versus high dose arms.

Sponsors

University of Chicago
Lead SponsorOTHER
Rush University Medical Center
CollaboratorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Intervention model description

2,000-person two-arm, double-blinded randomized controlled trial, with half the subjects randomized to low dose vitamin D therapy (400 IU/day), which will serve as the control group, and half to moderate (4,000 IU/day) or high (10,000 IU/day).

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes

Inclusion criteria

Subjects are able to participate if they: 1. Are 18 years or older. 2. Live or work in the Chicagloland area (Illinois counties: Cook, Lake, McHenry, DuPage, Kane, Kendall, Grundy, Will, and Kankakee; Indiana counties: Lake and Porter). 3. 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 9-month study period. 4. Are willing to attend the laboratory for drop-in appointments at UChicago Medicine or Rush University Medical Center every 3 months at 4 time points over a 9-month period for blood draws measuring COVID-19 antibodies, calcium, vitamin D and PTH levels. 5. Are willing to complete self-report measures at 4 time points over the course of 9 months by completing a 15-minute survey at intake by telephone or via web and 10-minute web-based follow-up surveys. Subjects are excluded from study participation if they: 1. Report ever having a positive COVID-19 PCR test result 2. Report being pregnant, planning to become pregnant, and/or report breastfeeding during the study period. 3. Report a history of chronic kidney disease, including a history of abnormal GFR and/or creatinine. 4. Report a history of hyperparathyroidism. 5. Report a history of increased falls. 6. Report a history of hypercalcemia. 7. Report a history of gastrointestinal absorptive disorders, including having undergone bariatric surgery. 8. Report a history of kidney stones (1 in past year or 2 in lifetime). 9. 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. 10. Report taking D2. 11. Report a history of sarcoidosis. 12. Screen positive for hypercalcemia during the initial blood test or follow-up blood tests. 13. Screen positive for primary hyperparathyroidism during the initial blood test. 14. Screen positive for COVID-19 antibodies during the initial blood test. 15. Have vitamin D levels of \>100ng/mL at study start, or \>250ng/mL during follow-up labs. 16. Are unwilling to provide blood samples during quarterly blood tests. 17. Are unwilling to take daily vitamin D.

Design outcomes

Primary

MeasureTime frameDescription
SARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Up to 9-monthsFor this outcome, hazard models will be employed to assess the effect of each vitamin D dosing strategy on the outcome. We will first develop hazard ratios for between-group analyses on the primary outcome using log-rank tests, and then develop Cox proportional hazard models to model the hazard function on a set of covariates including but not limited to, moderate or high vitamin D dose, baseline vitamin D levels, age, gender, race, ethnicity, sun exposure, sleep habits, exposure of cohabitants, job type, and study site. We will also control for randomization date to adjust the underlying hazard function for COVID-19 prevalence over time. While our primary analysis will pool subjects randomized to either the moderate or high dose and compare them to low dose subjects, we will also perform secondary analyses comparing low to moderate and low to high and additional analyses that use post randomization vitamin D levels as time varying covariates.

Countries

United States

Participant flow

Recruitment details

Participants recruited at the UChicago Medicine main hospital on Chicago's South Side or south suburban Ingalls Hospital and Rush University Medical Center on Chicago's West Side. We planned to enroll 2,000 persons to achieve 80% power to identify a 25% reduction in incidence (P\<0.05). Recruitment began Nov. 23, 2020 and concluded Mar. 30, 2023. Pharmacy staff assigned participants to treatment using a blocked randomization list. 1475 persons consented and 923 randomized and received vitamin D.

Pre-assignment details

Of 1475 consenting participants, only 923 were randomized and received vitamin D after exclusions due to not completing baseline surveys or labs or baseline lab values that identified the participant did not meet inclusion criteria.

Participants by arm

ArmCount
Low Dose Vitamin D (Moderate Versus Low Branch)
Subjects in this arm will be randomized to receive low dose vitamin D therapy (oral, 400 IU/day) for up to 9 continuous months.
300
Moderate Dose Vitamin D
Subjects in this arm will be randomized to receive low dose vitamin D therapy (oral, 4,000 IU/day) for up to 9 continuous months.
299
Low Dose Vitamin D (High Versus Low Branch)
Subjects in this arm will be randomized to receive low dose vitamin D therapy (oral, 400 IU/day) for up to 9 continuous months.
162
High Dose Vitamin D
Subjects in this arm will be randomized to receive low dose vitamin D therapy (oral, 10,000 IU/day) for up to 9 continuous months.
162
Total923

Baseline characteristics

CharacteristicModerate Dose Vitamin DTotalLow Dose Vitamin D (Moderate Versus Low Branch)High Dose Vitamin DLow Dose Vitamin D (High Versus Low Branch)
Age, Continuous48.4 years
STANDARD_DEVIATION 14.6
47.0 years
STANDARD_DEVIATION 14.7
46.2 years
STANDARD_DEVIATION 15.4
45.0 years
STANDARD_DEVIATION 13.3
47.9 years
STANDARD_DEVIATION 14.8
Average Sun Exposure
30 min/day or less
219 Participants687 Participants212 Participants124 Participants132 Participants
Average Sun Exposure
Missing/not answered
27 Participants66 Participants24 Participants10 Participants5 Participants
Average Sun Exposure
More than 30 min/day
53 Participants170 Participants64 Participants28 Participants25 Participants
Baseline Vitamin D Level36.9 ng/ml
STANDARD_DEVIATION 15.4
35.9 ng/ml
STANDARD_DEVIATION 16.4
36.8 ng/ml
STANDARD_DEVIATION 16
34.7 ng/ml
STANDARD_DEVIATION 17.8
33.4 ng/ml
STANDARD_DEVIATION 17.2
COVID-19 Exposure Outside Work
Missing/not answered
26 Participants74 Participants30 Participants11 Participants7 Participants
COVID-19 Exposure Outside Work
No
218 Participants696 Participants222 Participants128 Participants128 Participants
COVID-19 Exposure Outside Work
Yes
55 Participants153 Participants48 Participants23 Participants27 Participants
Employment
Missing/not answered
2 Participants8 Participants3 Participants2 Participants1 Participants
Employment
No
53 Participants160 Participants51 Participants29 Participants27 Participants
Employment
Yes
244 Participants755 Participants246 Participants131 Participants134 Participants
Ethnicity (NIH/OMB)
Hispanic or Latino
27 Participants97 Participants28 Participants16 Participants26 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
269 Participants814 Participants268 Participants143 Participants134 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
3 Participants12 Participants4 Participants3 Participants2 Participants
Insomnia Severity Index
Missing/not answered
30 Participants73 Participants28 Participants10 Participants5 Participants
Insomnia Severity Index
Moderate or Severe
6 Participants40 Participants13 Participants11 Participants10 Participants
Insomnia Severity Index
No or Subthreshold
263 Participants810 Participants259 Participants141 Participants147 Participants
Race (NIH/OMB)
American Indian or Alaska Native
1 Participants2 Participants1 Participants0 Participants0 Participants
Race (NIH/OMB)
Asian
29 Participants81 Participants34 Participants11 Participants7 Participants
Race (NIH/OMB)
Black or African American
43 Participants126 Participants37 Participants19 Participants27 Participants
Race (NIH/OMB)
More than one race
4 Participants19 Participants8 Participants5 Participants2 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
1 Participants1 Participants0 Participants0 Participants0 Participants
Race (NIH/OMB)
Unknown or Not Reported
16 Participants65 Participants18 Participants13 Participants18 Participants
Race (NIH/OMB)
White
205 Participants629 Participants202 Participants114 Participants108 Participants
Randomization Date
Potential Participation after Omicron Arrival
252 Participants771 Participants252 Participants133 Participants134 Participants
Randomization Date
Potential Participation Only Before Omicron Arrival
47 Participants152 Participants48 Participants29 Participants28 Participants
Sex: Female, Male
Female
226 Participants690 Participants230 Participants119 Participants115 Participants
Sex: Female, Male
Male
73 Participants233 Participants70 Participants43 Participants47 Participants
Study Site
Rush U Medical Ctr
184 Participants506 Participants174 Participants73 Participants75 Participants
Study Site
UChicago Medicine
115 Participants417 Participants126 Participants89 Participants87 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
EG002
affected / at risk
EG003
affected / at risk
deaths
Total, all-cause mortality
0 / 3000 / 2990 / 1620 / 162
other
Total, other adverse events
0 / 3000 / 2990 / 1621 / 162
serious
Total, serious adverse events
0 / 3000 / 2990 / 1620 / 162

Outcome results

Primary

SARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)

For this outcome, hazard models will be employed to assess the effect of each vitamin D dosing strategy on the outcome. We will first develop hazard ratios for between-group analyses on the primary outcome using log-rank tests, and then develop Cox proportional hazard models to model the hazard function on a set of covariates including but not limited to, moderate or high vitamin D dose, baseline vitamin D levels, age, gender, race, ethnicity, sun exposure, sleep habits, exposure of cohabitants, job type, and study site. We will also control for randomization date to adjust the underlying hazard function for COVID-19 prevalence over time. While our primary analysis will pool subjects randomized to either the moderate or high dose and compare them to low dose subjects, we will also perform secondary analyses comparing low to moderate and low to high and additional analyses that use post randomization vitamin D levels as time varying covariates.

Time frame: Up to 9-months

Population: Secondary analysis includes participants seroconverting from negative to positive COV-NAb.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
Low Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Primary Analysis68 Participants
Low Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Secondary Analysis43 Participants
Pooled Moderate or High Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Primary Analysis50 Participants
Pooled Moderate or High Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Secondary Analysis31 Participants
Low Dose Vitamin D (moderate versus low branch)SARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Primary Analysis48 Participants
Low Dose Vitamin D (moderate versus low branch)SARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Secondary Analysis32 Participants
Moderate Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Primary Analysis30 Participants
Moderate Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Secondary Analysis17 Participants
Low Dose Vitamin D (high versus low branch)SARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Primary Analysis20 Participants
Low Dose Vitamin D (high versus low branch)SARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Secondary Analysis11 Participants
High Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Primary Analysis20 Participants
High Dose Vitamin DSARS-CoV-2 Infection as Measured by Patient Report of Clinically Confirmed COVID-19 (or Viral PCR When Available)Secondary Analysis14 Participants
Comparison: Pooled moderate or high versus low dosep-value: 0.195% CI: [0.51, 1.06]Regression, Cox
Comparison: Moderate versus low dosep-value: 0.04295% CI: [0.39, 0.98]Regression, Cox
Comparison: High versus low dosep-value: 0.9995% CI: [0.53, 1.86]Regression, Cox
Comparison: Secondary analysis, pooled moderate versus low dosep-value: 0.2695% CI: [0.27, 1.43]Regression, Logistic
Comparison: Secondary analysis, moderate versus low dosep-value: 0.0695% CI: [0.13, 1.04]Regression, Logistic
Comparison: Secondary analysis, high versus low dosep-value: 0.4795% CI: [0.41, 6.71]Regression, Logistic
Other Pre-specified

Death Following COVID-19

This will be measured by a binary indicator of whether the patient dies after COVID-19 in the first quarterly survey up to 9 months after COVID-19 is reported and will be analyzed with a generalized linear model with covariates as in the secondary outcome measure.

Time frame: 9 months

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Low Dose Vitamin DDeath Following COVID-190 Participants
Pooled Moderate or High Dose Vitamin DDeath Following COVID-190 Participants
Low Dose Vitamin D (moderate versus low branch)Death Following COVID-190 Participants
Moderate Dose Vitamin DDeath Following COVID-190 Participants
Low Dose Vitamin D (high versus low branch)Death Following COVID-190 Participants
High Dose Vitamin DDeath Following COVID-190 Participants
Other Pre-specified

Hospitalization Following COVID-19

This will be measured by a binary indicator of whether the patient is hospitalized after COVID-19 in the first quarterly survey after COVID-19 is reported and will be analyzed with a generalized linear model with covariates as in the secondary outcome measure.

Time frame: 9 months

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Low Dose Vitamin DHospitalization Following COVID-190 Participants
Pooled Moderate or High Dose Vitamin DHospitalization Following COVID-190 Participants
Low Dose Vitamin D (moderate versus low branch)Hospitalization Following COVID-190 Participants
Moderate Dose Vitamin DHospitalization Following COVID-190 Participants
Low Dose Vitamin D (high versus low branch)Hospitalization Following COVID-190 Participants
High Dose Vitamin DHospitalization Following COVID-190 Participants
Other Pre-specified

ICU Stay Following COVID-19

This will be measured by a binary indicator of whether the patient is admitted to the ICU after COVID-19 in the first quarterly survey after COVID-19 is reported and will be analyzed with a generalized linear model with covariates as in the secondary outcome measure.

Time frame: 9 months

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Low Dose Vitamin DICU Stay Following COVID-190 Participants
Pooled Moderate or High Dose Vitamin DICU Stay Following COVID-190 Participants
Low Dose Vitamin D (moderate versus low branch)ICU Stay Following COVID-190 Participants
Moderate Dose Vitamin DICU Stay Following COVID-190 Participants
Low Dose Vitamin D (high versus low branch)ICU Stay Following COVID-190 Participants
High Dose Vitamin DICU Stay Following COVID-190 Participants
Other Pre-specified

Ventilator Use Following COVID-19

This will be measured by a binary indicator of whether the patient receives mechanical ventilation after COVID-19 in the first quarterly survey after COVID-19 is reported and will be analyzed with a generalized linear model with covariates as in the secondary outcome measure.

Time frame: 9 months

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
Low Dose Vitamin DVentilator Use Following COVID-190 Participants
Pooled Moderate or High Dose Vitamin DVentilator Use Following COVID-190 Participants
Low Dose Vitamin D (moderate versus low branch)Ventilator Use Following COVID-190 Participants
Moderate Dose Vitamin DVentilator Use Following COVID-190 Participants
Low Dose Vitamin D (high versus low branch)Ventilator Use Following COVID-190 Participants
High Dose Vitamin DVentilator Use Following COVID-190 Participants

Source: ClinicalTrials.gov · Data processed: Jul 23, 2026