Vitamin D and COVID-19: What We Know at This Time

Vitamin D is essential for normal human functioning, but just how much is necessary has been a subject of debate and whether supplementing vitamin D in people who have “normal” levels can be beneficial in the prevention or treatment of certain diseases has been a subject of controversy for decades, largely due to the lack of high-quality studies.

While some will argue that the level of normal vitamin D should be set higher than current guidelines, I think that you would find a general consensus that an adult is vitamin D deficient if their serum 25-hydroxyvitamin D level is < 50 nmol/L or 20 ng/ml. There would also likely be agreement that treatment with vitamin D supplementation in individuals with serum 25-hydroxyvitamin D levels of < 30 nmol/L or 12 ng/ml is beneficial and very important for overall health.

Many people promoted the need for vitamin D supplementation to prevent and/or treat COVID-19 when the pandemic first began (in fact, a number of people continue to promote this idea). Unfortunately, we had little data or clinical studies at that time to answer that question. However, two years later, we know a lot more. Here are some key points:

  1. A study from Italy showed that a low serum vitamin D level was an independent risk factor for developing severe COVID-19 (mean 18.2 ng/ml) and dying (mean 13.2 ng/ml) from it, if a patient with low vitamin D gets infected.
  2. Unfortunately, studies have not been able to demonstrate that giving high doses of vitamin D once the patient with low vitamin D gets infected will reverse the risks for severe disease, hospitalization, the need for intensive care, mechanical ventilation or death.
  3. Some persons have a genetic abnormality that causes them to have high levels of vitamin D, but studies have demonstrated that these folks do not have a lower risk of getting infected or if infected, having less severe disease or risk of hospitalization and death.

Guidelines from the Endocrine Society recommend the following dietary intake of vitamin D:

  • Children aged 1-18 years: ≥ 600 IU/d
  • Adults aged 19-70 years: ≥ 600 IU/d
  • Adults older than 70 years: ≥ 800 IU/d

So, above, I have provided you with the state of the science. But now, here are my thoughts and how I put all this together:

  1. If you have vitamin D deficiency, it makes sense to take a daily vitamin D supplement. My vitamin D levels have been low and I take a daily supplement. If you have low levels of vitamin D, you may be at higher risk if infected.
  2. The fact that people with low vitamin D levels are at increased risk for severe disease if infected, but supplementing with vitamin D once infected doesn’t improve outcomes, as well as the fact that those with high vitamin D levels are not protected from developing severe disease suggests to me that vitamin D is likely only one factor in this risk for severe disease and may not even be the most important factor. Thus, if you get infected, please don’t rely on vitamin D and other supplements to keep you from getting severely ill. Seek medical attention from a physician and explore options that have been proven to improve outcomes if you are at high risk for severe disease, such as antiviral medications and monoclonal antibodies. I have no objection to taking vitamin D if you get infected, my point is simply that you should not rely on vitamin D or any other supplements to keep you from getting severely ill.

20 thoughts on “Vitamin D and COVID-19: What We Know at This Time

  1. Can getting some sunshine on a regular basis help prevent vitamin D deficiency, and thus help protect against severe COVID-18 infections?


  2. Great blog. Thank you telling this. I hope all those I copy will read and hear the message DuWayne Sent from my iPhone



  3. Dr. Pate
    I heard you speak on Idaho matters today. It was informative and refreshing to hear someone speak as honestly and clearly as you do. It has been more and more difficult to understand what is true these days. Thank you so much for your contributions.
    B. White Eagle


    1. Thank you so much for taking the time and making the effort to provide me with this comment and the encouragement. I greatly appreciate it. And, thanks for following my blog!


  4. Hi Dr. Pate,

    What are your thoughts with regard to immunocompromised people getting a 4th dose of the Pfizer vaccine? With the positivity rate on the decrease and continuous COVID19 treatment advancements, is there any reason to wait?

    I really appreciate the great service you provide for our community. Thank you, thank you!


    1. Thanks, Don. Great question. I think that this is exactly the right time to get your booster. Getting a booster during the next surge means you will be at increasing risk for a period of 7 – 14 days as disease transmission is rapidly increasing. Getting boosted now means you will be protected for the next surge. I wish that I agreed with those who are saying that we won’t see any more surges or at least we should have smooth sailing until this fall/winter, but I don’t believe either of those scenarios are likely. Right now, I only feel confident in saying I don’t think we will have another surge in the next 1 -2 weeks. I hope it is much longer, but certainly can’t guarantee it.
      Thanks for your comment and your question and thanks for following my blog!


    1. While vitamin D replacement is definitely warranted in those who are vitamin D deficient, so far, clinical trials of administering vitamin D to patients hospitalized with COVID-19 did not show any benefit.

      Thanks for following my blog.


    2. Thank you for the articles you submitted in support of treatment with vitamin D. There certainly are some studies suggesting effectiveness, but others failing to show a benefit. The problem is getting large enough numbers of patients to sufficiently power the studies and having sufficient trial design to eliminate confounding factors. One certainly must be cautious in coming to conclusions when studies do not consistently show benefit – a sign that there is more to the story. I certainly have no problem with any physician who wants to treat patients with vitamin D. However, given that vitamin D is off topic for current blog posts, I am not going to post the articles you submitted plus the articles I reviewed as I think because the data is confusing, it is likely to confuse most readers and I don’t want to take us all down a tangent at this time. Hopefully, we will find benefit to vitamin D in this setting because it is inexpensive and we certainly need more treatment options. Thanks!


      1. “others failing to show a benefit.”

        I have done my own reading of the literature, but I can recommend Sebastian Rushworth and David Grimes on vitamin D who look at some studies.

        The following question was my starting point in my self-education.

        Who was at risk for death from covid? The elderly, the obese, and people of color.

        Who is at risk for vitamin d deficiency? The elderly, the obese, and people of color.

        Next I asked, what about covid kills people? Immune-system-induced inflammation.

        Then I looked at how vitamin D works with the immune system. After infection is cleared, vitamin D reduces inflammation if calcifediol levels are high enough– >=40 ng/ml.

        I looked at meta studies of vitamin D supplementation and found that most of the negative studies supplemented with low doses of cholecalciferol in cohorts at low risk for vitamin D deficiency, while the positive studies either supplemented with high doses of cholecalciferol or with calcifediol doses aimed at raising 25OHD levels to 50 ng/ml on cohorts at high risk for hypovitaminosis D.

        So, it seems to take a certain process of evaluating the literature to come to a point where it becomes easier to separate the wheat from the chaff wrt vitamin D studies.


      2. Wow! You have done a great job thinking this through logically and I commend you on your research and I think you have made a number of really good points. I think what is difficult in conducting studies on vitamin D supplementation in order to conclude a benefit is one fact that you have already raised – differences in amounts of vitamin D administered, route of administration, the form of vitamin D and the duration of supplementation. In addition, in a condition like COVID-19, where there are so many mechanisms of immune dysfunction and immunopathology (we have covered a number of them in this blog series, but not all of them), while vitamin D is important to healthy immune functioning as you mentioned, I certainly don’t know any mechanism by which vitamin D would prevent some of the specific immune injuries we see such as infection of monocytes and lymphocytes. If you study vitamin D supplementation in a largely outpatient population with mild COVID-19, then you need huge numbers in order to statistically power any conclusion as to efficacy. On the hand, if you study it in hospitalized patients, where it doesn’t require such high numbers to show benefit, we often have the confounding problem that no ethics committee is going to approve treatment with only vitamin D, when we have other effective treatments, but then it becomes difficult to compare studies because we had different treatments at different times of the pandemic.

        I think that your concluding paragraph states it well. When it is this complicated and we have studies coming to completely different conclusions, it does take a lot of weeding through them to try to “separate the wheat from the chaff.”

        I certainly would not have any hesitation about treating patients with vitamin D, but I also would ensure that they get the treatments for which we have shown far more conclusively a clinical benefit.

        Thanks for your excellent question, thoughts and research on this!


      3. Let’s suppose that you give an antiviral and clear covid virus…how do you prevent progression to the inflammatory phase in high risk patients? What are your options? How does the body normally reduce inflammation after an infection? What might inhibit the normal route of reducing inflammation?


      4. All good questions. One key thing is that people actually clear the virus. We will be discussing the persistence of virus in some individuals leading to persistent antigenic stimulation as potentially being one pathophysiologic mechanism for the development of Long COVID in my next blog post. We will also address your question about the inflammatory phase that can result from the production of autoantibodies or due to the disruption to the complicated role of certain immune cells in calming down an overly exuberant immune response. So, these are good questions that will tee up our discussion in my next blog post. Stay tuned!


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