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.

Czech Advanced Technology and Research Institute Palacky University in Olomouc Hnevotinska 1333 5 77900 Olomouc Czech Republic

Institute of Immunology Nicolás Enrique Bianco Faculty of Medicine Universidad Central de Venezuela Los Chaguaramos Caracas 1040 Venezuela

Institute of Molecular and Translational Medicine Faculty of Medicine and Dentistry Palacky University in Olomouc Hnevotinska 1333 5 77900 Olomouc Czech Republic

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