Tehran University of Medical Sciences Journal of Medical Bacteriology 2251-8649 12 2 2024 04 17 9 18 Nasim Kazemi Noraldinvand none Haniyeh Bashizadehfakhar Department of Human Geneticse, Science And Research Branch, Branch, Islamic Azad University, Tehran, Iran Forouzan Rostami 0000-0002-6729-3202 Shaghyegh Rangraz 0000-0003-3351-3921 Parnian Sadat Shahidi 0000-0003-4780 -5327 2023 12 13 2024 02 20 Background:   In 2019, the first cases of an acute respiratory infectious disease were announced in the city of Wuhan, China. In places where the speed of transmission and the resulting high prevalence and death from this virus is high, it is important to find things that help prevent and reduce the symptoms and complications of the disease, one of these things. Things are serum levels of vitamin D. As a result of this study, serum levels of vitamin D were measured in patients with Covid-19. Methods:   From December to March of 1400, 100 samples of people hospitalized in Khurshid laboratory were examined to identify the RNA of the Covid-19 virus by Real Time PCR method and at the same time to check the serum levels of vitamin D. The data was statistically analyzed using SPSS software. Results:   The average age of the patients was between 12.45 and 40.8 years. Comparison the two Covid-19 positive and negative groups in terms of symptoms, it was found that the patients with RH positive had more positive PCR percentage and a significant difference was reported between RH positive and Covid-19 (p=0.006). In comparing the relationship between disease symptoms and the rate of PCR positive reports of gastrointestinal symptoms, history of significant disease, cough, fever, a significant difference was reported (p<0.001). Also, 50% of the samples were PCR positive. Based on the t-test, a significant difference was reported between the serum levels of vitamin D and  Covid-19 (p<0.001). Conclusion:   The results showed that the vitamin D is an acceptable protective factor against  Covid-19 infection and its deficiency increases the probability of infection. https://jmb.tums.ac.ir/index.php/jmb/article/view/505