Abstract
Background: Vaccines are crucial for preventing infectious diseases, as both humoral and cellular immune responses play a vital role in combating viral infections. The cellular immune response is crucial against SARS-CoV-2, particularly with the emergence of new variants that evade antibody neutralization. This study focuses on the immune memory response in individuals who have been vaccinated with the Sinopharm BBIBP-CorV vaccine. Methods: A cross-sectional study evaluated lymphocyte subpopulations using flow cytometry in 52 vaccinated adults (30 females, 22 males) who had been exposed to SARS-CoV-2 or diagnosed with COVID-19. Conducted from February to June 2023 during the Omicron variant's circulation, this study assessed antigens-CD154 in CD4+ T cells, CD107 and CD314 in CD8+ T cells, CD314 in NK cells, and CD86 in CD19 B cells-after stimulation with viral peptides and an inactivated virus. Granzyme B and IFN-γ were quantified using ELISA. Results: The memory response, regardless of gender, age, or Body Mass Index (BMI), was mild but significant upon exposure to a viral antigen or inactivated virus. An increase in the secretion of IFN-γ and granzyme B was also observed. Conclusions: It is suggested that the vaccine was able to generate a mild long-term memory against the SARS-CoV-2 virus in vaccinated adult individuals, independent of gender and BMI.