The goal of this clinical trial study is to investigate the role of anthropometric indices and Vit-D supplementation on BioNTech, Pfizer vaccine side effect and immunoglobulin G response against SARS-CoV-2 in individuals infected with COVID-19.

The main question[s] it aims to answer are:

1. BMI has role in reduce BioNTech, Pfizer vaccine side effect
2. BMI has role in improve IgG titer
3. Vit-D supplementation has role in reduce BioNTech, Pfizer vaccine side effect
4. Vit-D supplementation has role in improve IgG titer

The intervention group received 600IU of vitamin D supplements every day, one hour after breakfast, for 14-16 weeks. The control group took a placebo prepared with the same shape and size of supplements. The supplement was given to the patients by someone other than the researcher, to ensure that the researchers did not know which group receiving the supplement/placebo (given the double-blindness of the study). Also, in this study, the person who did the data analysis did not aware of randomization. at first, a 3-day recall food questionnaire was taken from two groups. From the day, the subjects tested positive, they were asked to start supplementation for 4 weeks and return after that to take the first dose of the vaccine. Subjects were asked to continue to use supplements after the first vaccination. After 6 to 8 weeks, patients came back for another vaccination dose and were again asked to use the supplement for 4 weeks again, after that subjects were asked to come for a blood test.

Inclusion criteria:

participants with COVID-19 positive tests.

Exclusion criteria:

1. Who did not take the vaccine
2. who take one dose of the vaccine
3. who did not come back for another dose
4. subjects who in the last 6 months received vitamin or mineral supplementation
5. those with chronic conditions such as diabetes, hypertension, and heart disease, unwillingness to continue the study protocol, lactating women and pregnant women.