Vitamin D is a gene modulator. It is also known to modulate many aspects of immune function, including adaptive and innate processes. Studies have shown that:

· A high level of vitamin D in the blood is associated with a decreased infection rate by SARS-CoV-2.

· High vitamin D levels are associated with a reduced risk of severe cases of COVID-19 (involving hospitalization, ICU, or mortality).

· Intervention studies and randomized controlled trials have shown that vitamin D can be a very effective treatment.

· Several publications have revealed the mechanism by which vitamin D affects COVID-19.

· It is also important to note that Hill’s criteria, causal inference modeling, intervention studies, and biological mechanisms show that the influence of vitamin D on COVID-19 is more causal, not just correlation.

Vitamin D is an essential fat-soluble vitamin

However, studies have shown that many people do not get enough of it. Medically, there are two definitions of the inadequacy of vitamin D: deficiency and insufficiency.

For deficiency, the intake is <20ng/ml (50 nmol/L). For insufficiency, intake is < 30ng/ml (75 nmol/L). The truth is that many people take far below these targets. Rates of vitamin D deficiency are higher in winter. The deficiency is worse in specific groups: overweight, people with dark skin (staying far from the equator), and people residing in care homes. These groups also have an increased risk of COVID-19.

Vitamin D national guidelines need to be updated

Studies have shown that 97.5% of people require a daily dose of 97mcg (3875 IU) to reach 20ng/ml and 155mcg (6200 IU) to reach 30ng/ml. These intakes exceed national guidelines.

Current evidence suggests a tendency of the pandemic to sustain itself primarily via infection of those deficient in vitamin D, and death rates are higher in those with vitamin D deficiency. The possibility that this is true should compel the collation of more vitamin D.

Is too much vitamin D toxic?

Safety data collated for decades show that vitamin D has a shallow risk: toxicity would be a sporadic occurrence with these recommendations. The dangers of deficiency far outweigh whatever risks from levels that appear to protect COVID-19, which differs immensely from different drugs. Vitamin D has a higher safety level than steroids, like dexamethasone. The safety provided by vitamin D is also more like that of face masks.

The healthcare experts recommended that all governments, healthcare workers, and doctors recommend and implement efforts to increase vitamin D intake among their adult populations, all through the pandemic period.