We don’t have a Covid-19 vaccine yet. So, this is a hypothetical comparison: which might be more effective in reducing Covid-19 infection rate and death rate (A) vaccinate the population, or, (B) program to increase 25(OH)D levels to the middle of normal range (about 50 to 60 ng/ml)?

First things First: I’m in favor of Covid-19 vaccines as an important part of the world’s response to the pandemic. We need multiple safe and effective vaccines to fight this plague. However, vaccines are not the only or the main way to defeat the disease. This particular virus is too good at fighting the immune system to rely solely on a vaccine (see this article). This pandemic is real and very dangerous, and vaccines are necessary. But it’s a mistake to rely mainly or only on a vaccine.

Group A: Suppose, hypothetically, that one thousand persons were vaccinated with a Covid-19 vaccine that is 50% effective at preventing infection. 50% was chosen because the CDC says that the yearly flu vaccine is typically 40 to 60% effective at preventing the flu. Let’s also propose that the vaccine, when it does not prevent infection with Covid-19, at least reduces the severity of the disease in another 25 percentage points of the population. So we would have a 50% reduction in Covid-19 cases and a 75% reduction in Covid-19 deaths. The 75% comes from the 50% who do not contract the disease, plus the 25% who, if they get sick, don’t die because of reduced severity.

So that’s a 50% reduction in infection rate and a 75% reduction in mortality.

Group B: Suppose also that another group of one thousand persons are given vitamin D, so that their blood levels of 25(OH)D are 50 to 60 ng/ml (125 to 150 nmol/liter). Why use that range? A new study by Kaufman et al. [1] found that at 55 ng/ml patients had less than half the risk of infection with SARS-CoV-2 than persons with 25(OH)D levels of 20 ng/ml or less. So if everyone is over 50 ng/ml, you have the same 50% reduction as with a vaccine that is 50% effective.

And we have vitamin D now; we don’t yet have a vaccine. Then, too, vaccines have serious side effects; whereas vitamin D supplementation is unlikely to cause any side effects. One vaccine study found that all vaccinated persons had side effects; most persons taking vitamin D have no side effects. Vitamin D is cheaper than a vaccine; you can get it for free from sunlight. Vaccines require a visit to a place where you might become infected with Covid-19. Vitamin D is available by mail without a prescription.

What is the reduction in Covid-19 mortality? Carpagnano [2] study: “after 10 days of hospitalization, severe vitamin D deficiency patients had a 50% mortality probability, while those with vitamin D ≥10 had a 5% mortality risk (p=0.019).” There’s a ten times greater risk of death from Covid-19 with vitamin D deficiency. Removing vitamin D deficiency removes most deaths.

The hypothetical vaccine reduces deaths 75%, the use of vitamin D reduces deaths by perhaps 90%. This would mean that raising everyone’s vitamin D levels to 50+ ng/ml is more effective than the described hypothetical vaccine at reducing deaths, and just as effective at reducing infection risk.

Greater Complexity

The above scenario is an oversimplified explanation, used to make the comparison as clearly as possible. Now let’s bring the scenario closer to real world.

In any vaccine, persons for whom the vaccine does not work will tend to be persons with weakened immune systems. Vaccines prompt your immune system to produce antibodies, and in some vaccines T-cells, so as to be ready to fight the disease. Antibodies and T-cells are part of the adaptive immune system, which has to “learn” to recognize a viral protein as foreign in order to attack it. The vaccine trains the immune system. However, with a weakened immune system, a person might not react to a vaccine by producing antibodies or T-cells, at least not with a strong enough reaction for full protection. So if the vaccine is 50% effective, the other half, who don’t produce sufficient antibodies for protection have weaker immune systems than the half for whom the vaccine works. That reduces the effectiveness of the vaccine, especially at reducing deaths. You might have a 50% reduction in cases from the vaccine, but the reduction in deaths would probably be less than the 75% previously discussed for the vaccine.

In any vitamin D supplementation program, there will be persons who are not compliant. They will not take the supplements, nor will they get out in the sun. But the question for this type of comparison with a vaccine program is which will have greater compliance? It seems more likely that people would take a pill than get a shot. On the other hand, the pill must be taken daily for the first month, then weekly afterward; by comparison, the vaccine shot will probably require two, maybe three visits to whoever gives out the shot. I think the vitamin D pill will have greater compliance. Therefore, if the vaccine and vitamin D each reduce the infection rate by 50%, in reality the vaccine will reduce it less than 50%, due to a lower compliance.

A problem unique to the vitamin D program will be the range of blood levels. We might target a range of 50 to 60 ng/ml, for maximum reduction in the infection rate, but some persons will not reach that range, especially: those that are less compliant and don’t always take the supplement, or who refuse to take a high enough dosage; those who are obese or who have problems with liver or kidneys, needed to process the supplement; those simply starting out with a very low level of vitamin D, so that it takes longer to reach the desired range. With a lower vitamin D level, there would be a lower benefit.

Now, some persons will complain about this comparison, saying we don’t have enough studies on vitamin D and Covid-19, or that the vitamin D studies are correlations, not causation, et cetera. On that last point, every study that seeks a correlation, is actually seeking causation. It’s a misleading oversimplification to say, as they often say on the internet or in the mass media, “Ah-ha, but correlation is not causation!” Yes, I know that. We ALL know that. But did YOU know that studies use statistical analysis to eliminate, as much as possible, various confounding variables, so as to determine if the correlation is caused by a confounder or whether it is causation? And as the studies finding a correlation, with multivariate analysis, accumulate, we move ever closer to establishing causation. At this point, with over two dozen studies on vitamin D and Covid-19, there is a reasonable degree of likelihood that vitamin D does cause a reduction in infection rate and especially in severity and mortality from Covid-19.


I am not proposing that a vitamin D supplementation program replace a vaccination program. I am not proposing that vitamin D is necessarily more effective than a vaccine. It’s certainly possible for a vaccine to be 75 to 95% effective, in which case it might be more effective than a vitamin D program.

What am I proposing? That we do BOTH a vaccination program and a vitamin D program. And since we currently have vitamin D, and we do not yet have a vaccine, let’s start the vitamin D programs NOW. Right f@#$ing now. There is no time to lose. The longer we wait, the more lives that are unnecessarily lost.

Ronald L. Conte Jr.
“I am an author, not a physician or healthcare professional.”

1. Kaufman HW, et al. “SARS-CoV-2 positivity rates associated with circulating 25-hydroxyvitamin D levels.” (2020) PLoS ONE 15(9): e0239252. Study Link

2. Carpagnano, Giovanna Elisiana, et al. “Vitamin D deficiency as a predictor of poor prognosis in patients with acute respiratory failure due to COVID-19.” Journal of Endocrinological Investigation (2020): 1-7.