Mahdi Vahabi

Background and Aims: Several factors influence the response to the vaccine, including age, gender, pregnancy, microbiota composition, immune function, sex hormones, and micronutrients (such as vitamin D). This study aimed to evaluate antibody responses induced by the BBIBP‐CorV vaccine in pregnant women and investigate its association with serum vitamin D levels. Methods: Serum samples were collected from 140 pregnant women 1–2 months after administering the second dose of the BBIBP‐CorV vaccine from August 2021 to April 2022. IgG antibody titers against RBD and serum vitamin D levels were measured using enzyme‐linked immunosorbent assay (ELISA). The relationship between vitamin D levels and anti‐RBD IgG antibody titer was investigated with linear regression analysis. Results: Anti‐RBD IgG antibodies were detected in 17% (24 out of 140) of the population studied. A positive correlation was observed between serum vitamin D level and anti‐RBD IgG antibody titer ( p < 0.001). Conclusion: Our study showed that two doses of the BBIBP‐CorV vaccine elicited antibody responses against COVID‐19 in only a small proportion of pregnant women, suggesting that higher doses or alternative vaccine platforms may be required to protect pregnant women. Despite the existence of a relationship between vitamin D levels and antibody response in our study, prospective clinical trial studies are needed to draw definitive conclusions regarding the effect of vitamin D on antibody response.