COVID-19Phase 3VIVIDNCT04536298
Vitamin D for COVID-19 Trial
A Phase 3 study testing vitamin D in people with COVID-19, run by Brigham and Women's Hospital at 1 site in United States.
Trial summary
The Vitamin D for COVID-19 Trial (VIVID) is a randomized, placebo-controlled clinical trial in 2024 men and women from across the U.S. and Mongolia to investigate whether taking a daily dietary supplement of vitamin D vs. 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
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 2,024 participants
- Where
- 1 siteUnited States
- Study dates
- 28 Dec 2020to 1 Jul 2024
- Phase
- Phase 3
- 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
- Adults aged 18 years or older who are newly diagnosed with COVID-19 infection within 7 days of testing.
- Ability and willingness to understand and provide informed consent.
- Persons aged 18 years or older who live in the same household with an index individual and have been identified as the closest household contact within the same household (limited to 1 per household).
- Persons aged 18 years or older who live in household with someone who tested positive for COVID-19 within past 7 days but not participating in VIVID.
- Ability and willingness to understand and provide informed consent.
Who cannot join
- Known current pregnancy.
- Current hospitalization.
- Unable to complete online questionnaires or adhere to study requirements.
- Consume more than 1000 IU per day of vitamin D from all supplemental sources combined (individual vitamin D supplements, calcium plus vitamin D supplements, medications with vitamin D [e.g., Fosamax Plus D], and multivitamins) in the past 4 weeks.
- Use of prescription vitamin D treatments (Calcitriol [Rocaltrol, Calcitrol, Vectical, Calcijex] or Paricalcitol [Zemplar]).
- Consume supplements with more than 1200 mg calcium per day.
Show all 29Show fewer
- Known diagnosis of hypercalcemia or a condition associated with vitamin D hypersensitivity.
- Prior diagnosis of cancer *AND* currently undergoing radiation, chemotherapy, or immunotherapy.
- Kidney failure or dialysis; severe liver disease or cirrhosis.
- Any parathyroid conditions.
- Use of medications for seizures or epilepsy. Examples: Carbamazepine (Carbatrol, Tegretol), Phenytoin (Dilantin, Phenytek), Valproic acid (Depakene), Oxcarbazepine (Oxtellar, Trileptal), Phenobarbital, Topiramate (Topamax).
- Use of digoxin.
- Inability to receive an overnight express mail shipment of study pills at a home address.
- Participation in other COVID-19 trials.
- Known current pregnancy.
- History of SARS-CoV-2 infection.
- Receipt of a SARS-CoV-2 vaccination or monoclonal antibody.
- Unable to complete online questionnaires or adhere to study requirements.
- Consume more than 1000 IU per day of vitamin D from all supplemental sources combined (individual vitamin D supplements, calcium plus vitamin D supplements, medications with vitamin D [e.g., Fosamax Plus D], and multivitamins) in the past 4 weeks.
- Use of prescription vitamin D treatments (Calcitriol [Rocaltrol, Calcitrol, Vectical, Calcijex] or Paricalcitol [Zemplar]).
- Consume supplements with more than 1200 mg calcium per day.
- Known diagnosis of hypercalcemia or a condition associated with vitamin D hypersensitivity.
- Prior diagnosis of cancer *AND* currently undergoing radiation, chemotherapy, or immunotherapy.
- Kidney failure or dialysis; severe liver disease or cirrhosis.
- Any parathyroid condition.
- Use of medications for seizures or epilepsy. Examples: Carbamazepine (Carbatrol, Tegretol), Phenytoin (Dilantin, Phenytek), Valproic acid (Depakene), Oxcarbazepine (Oxtellar, Trileptal), Phenobarbital, Topiramate (Topamax).
- Use of digoxin.
- Inability to receive an overnight express mail shipment of study pills at a home address.
- Participation in other COVID-19 trials.
Trial locations and contacts
1 site in 1 country.
United States1 site
Brigham and Women's Hospital
Boston, Massachusetts, 02215
About this study
Official title: A Cluster-Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy of Vitamin D3 Supplementation to Reduce Disease Severity in Persons With Newly Diagnosed COVID-19 Infection and to Prevent Infection in Household Members
The Vitamin D for COVID-19 Trial (VIVID) is a randomized, placebo-controlled clinical trial in 2024 men and women from across the U.S. and Mongolia to investigate whether taking a daily dietary supplement of vitamin D vs. placebo for 4 weeks reduces the rate of seeking healthcare for symptoms or concerns related to COVID-19 in participants recently diagnosed with COVID-19, and reduces the risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in household contacts of individuals with newly diagnosed COVID-19.
Read the detailed description
Data from laboratory studies, epidemiologic research, and randomized clinical trials conducted in the pre-COVID era strongly suggest that vitamin D is active in pathways relevant to immune function and may reduce the risk of acute respiratory infections. More recently, some observational studies have shown a significant association between low vitamin D status and worse clinical outcomes among COVID-19 patients. Whether vitamin D supplementation can reduce the risk of adverse clinical outcomes in recently diagnosed COVID-19 patients and/or reduce risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV- 2) in those likely to have been exposed to the virus (post-exposure prophylaxis) is unknown.
The Vitamin D for COVID-19 Trial (VIVID) is a pragmatic, cluster-randomized clinical trial in 2024 men and women recruited nationwide from the U.S. and Mongolia. The trial is investigating whether taking a daily dietary supplement of vitamin D3 vs. placebo for 4 weeks reduces the rate of seeking healthcare visits (including hospitalizations, emergency room visits, or ambulatory or virtual clinician visits) for symptoms or concerns related to COVID-19 or deaths in people newly diagnosed with COVID-19, and reduces the risk of SARS-CoV-2 infection in household contacts of individuals with newly diagnosed COVID-19.
The trial has enrolled 1747 individuals aged 18 or older who are newly diagnosed with COVID-19 ("index cases") and 277 household contacts aged 18 or older.
Following receipt of informed consent, participants are randomized -- i.e., assigned by chance (like a coin toss) -- to one of two groups: (1) daily vitamin D3 (9600 IU/day on days 1-2; 3200 IU/day on days 3-28) or (2) daily vitamin D placebo. Index cases and household contacts of an index case (limited to at most one contact per household), if any, are assigned to the same group (cluster randomization). Participants take three oral softgel capsules on day 1, three capsules on day 2, and one capsule each day on days 3 through 28. Participants receive a 4-week supply of study capsules via overnight courier service.
Participants fill out a short (15-20 minute) questionnaire each week during the 4-week pill-taking period, as well as a follow-up questionnaire at 8 weeks after randomization. These questionnaires ask about symptoms, general health, and use of medications and dietary supplements. Questionnaires are completed online using a secure Internet-based system known as the Research Electronic Data Capture (REDCap) system. Participants must have an e-mail address to enroll in the study. Occasionally, participants (or their delegates) may receive a telephone call from study staff to collect information or to clarify answers on the questionnaire. Participants may contact investigators or staff using a toll-free number, if they have any questions or need assistance.
Participants (or their delegates) who indicate on a study questionnaire that they have been hospitalized are sent a medical release form to be signed and returned. The release form is used to get medical records from the participant's physician or hospital to confirm the specific reason for the hospitalization. In the event of a participant's death, the participant's delegate is sent a medical release form to be signed and returned. The release form is used to get medical records from the participant's physician or hospital to confirm the specific cause of death.
Participants provide dried blood spot samples at baseline and week 4. Participants provide these samples using a sample collection kit mailed to their homes. Blood samples are collected through a finger prick onto a filter paper. Blood samples are stored and will be used to measure vitamin D (25(OH)D) levels. A subsample of participants provide follow-up dried blood spot samples at weeks 1, 2, or 3 to clarify the time course of 25(OH)D increase. In participants who are not diagnosed with COVID-19 during the study, blood samples will also be tested for COVID-19 antibodies.
Support for VIVID is provided by Harvard University and private philanthropy. Tishcon Corporation (Salisbury, Maryland, USA) is donating the study capsules. The Karolinska Institute (Stockholm, Sweden) is donating the serology assessment.
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
vitamin DDietary supplement
Also called vitamin D3, cholecalciferol
Vitamin D softgel capsules; each capsule contains 3200 IU of vitamin D3. Three capsules per day (9600 IU/day) will be taken on days 1 and 2, and one capsule per day (3200 IU/day) will be taken on days 3 through 28
PlaceboDietary supplement
Placebo softgel capsules. Three capsules per day will be taken on days 1 and 2, and one capsule per day will be taken on days 3 through 28
| Study group | Role | What they receive |
|---|---|---|
| Vitamin D | Active comparator | Daily vitamin D3 (9600 IU/day on days 1 and 2; 3200 IU/day on days 3 through 28) Receives: Dietary Supplement: vitamin D |
| Placebo | Placebo comparator | Placebo Receives: Dietary Supplement: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Rate of seeking healthcare visits (including hospitalizations, emergency room visits, or ambulatory or virtual clinician visits) for symptoms or concerns related to COVID-19 or deaths in participants newly diagnosed with COVID-19 (index cases)
Measured: 4 weeks
Secondary outcomes (6)
Rate of in-person healthcare visits related to COVID-19 infection among index cases
Measured: 4 weeks
Disease symptom score in index cases
Area under curve (AUC) of weekly self-reported symptom score (summed across all symptoms) through week 4
Measured: 4 weeks
Disease severity in index cases
Self-report of at least one severe symptom
Measured: 4 weeks
Time to seeking healthcare (including hospitalizations, emergency room visits, or ambulatory or other clinician visits) or death in index cases
Measured: 4 weeks
SARS-CoV-2 infection in close household contacts
Self-report of positive test
Measured: 4 weeks
Long COVID symptoms in index cases
Measured: 8 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Sep 2020
- Study start28 Dec 2020
- Primary completion1 Jul 2024
- Study completion1 Jul 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for COVID-19Studies of the same condition, open and under way.
- More trials run by Brigham and Women's HospitalThe 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 3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 2,024 participants (actual)
Sponsor and investigators
- Lead sponsor
- Brigham and Women's Hospital
- Sponsor type
- University, hospital or other
- Collaborators
- Harvard Medical School (HMS and HSDM), Harvard School of Public Health (HSPH), Fenway Health and Beth Israel Deaconess Medical Center, Tishcon Corporation, Takeda, Quest Diagnostics-Nichols Insitute, Laboratory Corporation of America, Trialfacts, Karolinska Institutet, Philanthropic donations
- Responsible party
- Principal investigator, JoAnn E. Manson, MD, Brigham and Women's Hospital
- Investigators
- JoAnn E Manson, MD, DrPH, Principal investigator, Brigham and Women's HospitalRui Wang, PhD, Principal investigator, Harvard Medical School (HMS and HSDM)Davaasambuu Ganmaa, PhD, Principal investigator, Harvard School of Public Health (HSPH)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04536298
- Sponsor's protocol ID
- 2020P002815
- Acronym
- VIVID
- Status last verified
- Sep 2025
- First submitted
- 27 Aug 2020
- Last updated
- 24 Sep 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Details will be provided at a later date.
Publications
Manson JE, Bassuk SS. Commentary. Eliminating vitamin D deficiency during the COVID-19 pandemic: A call to action. Metabolism. 2020 Nov;112:154322. doi: 10.1016/j.metabol.2020.154322. Epub 2020 Jul 23. No abstract available.
PubMed 32712223Wang R, DeGruttola V, Lei Q, Mayer KH, Redline S, Hazra A, Mora S, Willett WC, Ganmaa D, Manson JE. The vitamin D for COVID-19 (VIVID) trial: A pragmatic cluster-randomized design. Contemp Clin Trials. 2021 Jan;100:106176. doi: 10.1016/j.cct.2020.106176. Epub 2020 Oct 10.
PubMed 33045402Ganmaa D, Cook KA, Khudyakov P, Enkhjargal D, Bilegtsaikhan T, Mayer KH, Clar A, Rueschman M, Balasubramanian R, Hazra A, Sesso HD, Stone VE, Copeland P, Friedenberg G, Smith DC, Lei Q, Lee T, McDonald EG, Enkhtsetseg T, Sumiya E, Narankhuu Y, Erdenetuya M, Tserendagva D, Landberg R, Roxhed N, Lagerstrom SR, Manson JE. A Randomized Trial of Vitamin D Supplementation and COVID-19 Clinical Outcomes and Long COVID: The Vitamin D for COVID-19 Trial. J Nutr. 2026 Apr;156(4):101398. doi: 10.1016/j.tjnut.2026.101398. Epub 2026 Mar 12.
PubMed 41826107
Study at a glance
From the registry record, last updated by the sponsor on 24 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Cluster-Randomized, Double-Blind, Placebo-Controlled Study to Evaluate the Efficacy of Vitamin D3 Supplementation to Reduce Disease Severity in Persons With Newly Diagnosed COVID-19 Infection and to Prevent Infection in Household Members
- ClinicalTrials.gov ID
- NCT04536298
- Acronym / sponsor ID
- VIVID / 2020P002815
- Conditions
- COVID-19
- Keywords
- COVID-19, SARS-CoV-2 infection, coronavirus, vitamin D, hospitalization, death, disease severity, treatment
- Phase
- Phase 3
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 2,024 participants (actual)
- Lead sponsor
- Brigham and Women's HospitalUniversity, hospital or other
- Collaborators
- Harvard Medical School (HMS and HSDM), Harvard School of Public Health (HSPH), Fenway Health and Beth Israel Deaconess Medical Center, Tishcon Corporation, Takeda, Quest Diagnostics-Nichols Insitute, Laboratory Corporation of America, Trialfacts, Karolinska Institutet, Philanthropic donations
- Study start
- 28 Dec 2020 (actual)
- Primary completion
- 1 Jul 2024 (actual)
- Study completion
- 1 Jul 2024 (actual)
- First posted
- 2 Sep 2020 (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 Vitamin D for COVID-19 Trial (VIVID) is a randomized, placebo-controlled clinical trial in 2024 men and women from across the U.S. and Mongolia to investigate whether taking a daily dietary supplement of vitamin D vs. placebo for 4 weeks reduces the rate of seeking healthcare for symptoms or concerns related to COVID-19 in participants recently diagnosed with COVID-19, and reduces the risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in household contacts of individuals with newly diagnosed COVID-19.
Detailed description
Data from laboratory studies, epidemiologic research, and randomized clinical trials conducted in the pre-COVID era strongly suggest that vitamin D is active in pathways relevant to immune function and may reduce the risk of acute respiratory infections. More recently, some observational studies have shown a significant association between low vitamin D status and worse clinical outcomes among COVID-19 patients. Whether vitamin D supplementation can reduce the risk of adverse clinical outcomes in recently diagnosed COVID-19 patients and/or reduce risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV- 2) in those likely to have been exposed to the virus (post-exposure prophylaxis) is unknown.
The Vitamin D for COVID-19 Trial (VIVID) is a pragmatic, cluster-randomized clinical trial in 2024 men and women recruited nationwide from the U.S. and Mongolia. The trial is investigating whether taking a daily dietary supplement of vitamin D3 vs. placebo for 4 weeks reduces the rate of seeking healthcare visits (including hospitalizations, emergency room visits, or ambulatory or virtual clinician visits) for symptoms or concerns related to COVID-19 or deaths in people newly diagnosed with COVID-19, and reduces the risk of SARS-CoV-2 infection in household contacts of individuals with newly diagnosed COVID-19.
The trial has enrolled 1747 individuals aged 18 or older who are newly diagnosed with COVID-19 ("index cases") and 277 household contacts aged 18 or older.
Following receipt of informed consent, participants are randomized -- i.e., assigned by chance (like a coin toss) -- to one of two groups: (1) daily vitamin D3 (9600 IU/day on days 1-2; 3200 IU/day on days 3-28) or (2) daily vitamin D placebo. Index cases and household contacts of an index case (limited to at most one contact per household), if any, are assigned to the same group (cluster randomization). Participants take three oral softgel capsules on day 1, three capsules on day 2, and one capsule each day on days 3 through 28. Participants receive a 4-week supply of study capsules via overnight courier service.
Participants fill out a short (15-20 minute) questionnaire each week during the 4-week pill-taking period, as well as a follow-up questionnaire at 8 weeks after randomization. These questionnaires ask about symptoms, general health, and use of medications and dietary supplements. Questionnaires are completed online using a secure Internet-based system known as the Research Electronic Data Capture (REDCap) system. Participants must have an e-mail address to enroll in the study. Occasionally, participants (or their delegates) may receive a telephone call from study staff to collect information or to clarify answers on the questionnaire. Participants may contact investigators or staff using a toll-free number, if they have any questions or need assistance.
Participants (or their delegates) who indicate on a study questionnaire that they have been hospitalized are sent a medical release form to be signed and returned. The release form is used to get medical records from the participant's physician or hospital to confirm the specific reason for the hospitalization. In the event of a participant's death, the participant's delegate is sent a medical release form to be signed and returned. The release form is used to get medical records from the participant's physician or hospital to confirm the specific cause of death.
Participants provide dried blood spot samples at baseline and week 4. Participants provide these samples using a sample collection kit mailed to their homes. Blood samples are collected through a finger prick onto a filter paper. Blood samples are stored and will be used to measure vitamin D (25(OH)D) levels. A subsample of participants provide follow-up dried blood spot samples at weeks 1, 2, or 3 to clarify the time course of 25(OH)D increase. In participants who are not diagnosed with COVID-19 during the study, blood samples will also be tested for COVID-19 antibodies.
Support for VIVID is provided by Harvard University and private philanthropy. Tishcon Corporation (Salisbury, Maryland, USA) is donating the study capsules. The Karolinska Institute (Stockholm, Sweden) is donating the serology assessment.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Vitamin D | Active comparator | Dietary Supplement: vitamin DDaily vitamin D3 (9600 IU/day on days 1 and 2; 3200 IU/day on days 3 through 28) |
| Placebo | Placebo comparator | Dietary Supplement: PlaceboPlacebo |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Adults aged 18 years or older who are newly diagnosed with COVID-19 infection within 7 days of testing.
- Ability and willingness to understand and provide informed consent.
- Persons aged 18 years or older who live in the same household with an index individual and have been identified as the closest household contact within the same household (limited to 1 per household).
- Persons aged 18 years or older who live in household with someone who tested positive for COVID-19 within past 7 days but not participating in VIVID.
- Ability and willingness to understand and provide informed consent.
Key exclusion criteria (29 listed)
- Known current pregnancy.
- Current hospitalization.
- Unable to complete online questionnaires or adhere to study requirements.
- Consume more than 1000 IU per day of vitamin D from all supplemental sources combined (individual vitamin D supplements, calcium plus vitamin D supplements, medications with vitamin D [e.g., Fosamax Plus D], and multivitamins) in the past 4 weeks.
- Use of prescription vitamin D treatments (Calcitriol [Rocaltrol, Calcitrol, Vectical, Calcijex] or Paricalcitol [Zemplar]).
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 DAlso: vitamin D3, cholecalciferolVitamin D softgel capsules; each capsule contains 3200 IU of vitamin D3. Three capsules per day (9600 IU/day) will be taken on days 1 and 2, and one capsule per day (3200 IU/day) will be taken on days 3 through 28 | Dietary supplement | Vitamin D |
| PlaceboPlacebo softgel capsules. Three capsules per day will be taken on days 1 and 2, and one capsule per day will be taken on days 3 through 28 | Dietary supplement | Placebo |
Primary outcome
Rate of seeking healthcare visits (including hospitalizations, emergency room visits, or ambulatory or virtual clinician visits) for symptoms or concerns related to COVID-19 or deaths in participants newly diagnosed with COVID-19 (index cases)
Time frame: 4 weeks
6 secondary outcomes
Rate of in-person healthcare visits related to COVID-19 infection among index cases
Time frame: 4 weeks
Disease symptom score in index cases
Time frame: 4 weeks
Disease severity in index cases
Time frame: 4 weeks
Time to seeking healthcare (including hospitalizations, emergency room visits, or ambulatory or other clinician visits) or death in index cases
Time frame: 4 weeks
SARS-CoV-2 infection in close household contacts
Time frame: 4 weeks
Long COVID symptoms in index cases
Time frame: 8 weeks
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 24 Sep 2025.
- Background: PubMed 32712223Manson JE, Bassuk SS. Commentary. Eliminating vitamin D deficiency during the COVID-19 pandemic: A call to action. Metabolism. 2020 Nov;112:154322. doi: 10.1016/j.metabol.2020.154322. Epub 2020 Jul 23. No abstract available.
- Background: PubMed 33045402Wang R, DeGruttola V, Lei Q, Mayer KH, Redline S, Hazra A, Mora S, Willett WC, Ganmaa D, Manson JE. The vitamin D for COVID-19 (VIVID) trial: A pragmatic cluster-randomized design. Contemp Clin Trials. 2021 Jan;100:106176. doi: 10.1016/j.cct.2020.106176. Epub 2020 Oct 10.
- Derived from this study: PubMed 41826107Ganmaa D, Cook KA, Khudyakov P, Enkhjargal D, Bilegtsaikhan T, Mayer KH, Clar A, Rueschman M, Balasubramanian R, Hazra A, Sesso HD, Stone VE, Copeland P, Friedenberg G, Smith DC, Lei Q, Lee T, McDonald EG, Enkhtsetseg T, Sumiya E, Narankhuu Y, Erdenetuya M, Tserendagva D, Landberg R, Roxhed N, Lagerstrom SR, Manson JE. A Randomized Trial of Vitamin D Supplementation and COVID-19 Clinical Outcomes and Long COVID: The Vitamin D for COVID-19 Trial. J Nutr. 2026 Apr;156(4):101398. doi: 10.1016/j.tjnut.2026.101398. Epub 2026 Mar 12.
- Individual participant dataSharing planned: Yes. Details will be provided at a later date.
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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.
JoAnn E Manson, MD, DrPH principal investigator
Brigham and Women's Hospital
Rui Wang, PhD principal investigator
Harvard Medical School (HMS and HSDM)
Davaasambuu Ganmaa, PhD principal investigator
Harvard School of Public Health (HSPH)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 3 study testing vitamin D in people with COVID-19, run by Brigham and Women's Hospital 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 29 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 24 Sep 2025. 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. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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?
Rate of seeking healthcare visits (including hospitalizations, emergency room visits, or ambulatory or virtual clinician visits) for symptoms or concerns related to COVID-19 or deaths in participants newly diagnosed with COVID-19 (index cases) (time frame: 4 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04536298, which also lists 3 linked publications.
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 24 Sep 2025.