Participants in the experimental group were given 150,000 IU (10 ml) of vitamin D3 supplementation, and it was used regularly for 2 months. From the first measurement, 2 more measurements were taken, 28 days apart, and a total of 3 measurements were taken from the participants.

No supplement was given to the control group. From the first measurement, 2 more measurements were taken, 28 days apart, and a total of 3 measurements were taken from the participants.

Only the experimental group (D) received the vitamin D supplement.

Compared to other coronaviruses, it was understood that there is an instant need for a vaccine to prevent SARS CoV-2 because of its faster transmission. However, it is very important to determine that the COVID-19 vaccine is immune to individuals, and it has been emphasized that Immunoglobulin G (IgG) levels are checked for immune testing and it is important that these levels are high. People's immune systems or nutritional levels are influential in the high rate or efficiency of immunoglobin levels Studies have reported that individuals with adequate and balanced nutrition have a stronger immune system

Since a treatment process is not clear at the beginning of the COVID-19 disease, these supplements, such as vitamin D, C, and B vitamin groups and zinc minerals, have been given to COVID-19 patients in the clinic. In addition, 25-Hydroxy(25(OH)) vitamin D deficiency is a common condition for these patients. Accordingly, skeletal system diseases, immune system diseases, inflammatory bowel diseases, respiratory tract infections, viral infections, etc. affect situations are also seen. The pathogenesis relationship of 25(OH) vitamin D with the COVID-19 pandemic is consistently seen in the clinical data. In addition, 25(OH) vitamin D deficiency has a negative effect on people with COVID-19. For this reason, it is thought that hospitalizations due to COVİD-19 are increasing In a way, it is claimed to be an important factor in the severe course of the disease.