A Comparative Study of The Effectiveness of Pfizer-BioNTech (BNT162b2), AstraZeneca (ChAdOx1nCoV-19) and Sinopharm (BBIBP-CorV) Vaccines in Eliciting Cell Mediated and Humoral Immunity in A Sample of Vaccinated Population from Iraq

Background: Vaccine development is not an easy task but is a top priority to restore normalcy for Coronavirus-19 disease (COVID-19) and achieve the herd immunity.
Objective: To compare the level and duration of humeral versus cellular immune response in vaccinated individuals at one and 8 months after second dose of three different vaccines to severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), namely Pfizer, AstraZeneca, and Sinopharm vaccines.
Methods: The level of neutralizing antibodies and the peripheral mononuclear cells proliferation (PBMC) activity and in vitro IFN-γ release by the S1 spike protein-stimulated T cells were monitored using isotype- and species- free competitive blocking ELISA, microculture tetrazolium assay (MTT) proliferation assay and an ELISA technique for the assessment of IFN-γ level in a cell culture supernatant, respectively.
Results: PBMC proliferation percentage and the concentration of the in vitro IFN-γ release were remarkably higher in 8 months than in 1-month post-2nd dose vaccination groups of the three vaccines studied in this study (P <0.0001). For the PBMC proliferation percentage, AstraZeneca vaccine induced much higher proliferation percentage than Pfizer and Sinopharm (P <0.01), which both showed very close PBMC proliferation (P >0.05).
Conclusion: AstraZeneca showed superior effect on inducing robust cellular immunity followed by Pfizer vaccine, while Sinopharm showed minimal cellular immune response induction. And for all vaccines, the cellular immunity increased with time over 8 months after vaccination. Moreover, Pfizer vaccine proved to be of highest and most durable neutralizing anti-RBD IgG antibodies and followed with Sinopharm and AstraZeneca vaccines.
Keywords: COVID-19, SARS-CoV-2, RBD, vaccine, neutralizing antibodies (nABs)
Citation: Jawad FMM, Abdulamir AS. A comparative study of the effectiveness of Pfizer-BioNTech (BNT162b2), AstraZeneca (ChAdOx1nCoV-19) and Sinopharm (BBIBP-CorV) vaccines in eliciting cell mediated and humoral immunity in a sample of vaccinated population from Iraq. Iraqi JMS. 2024; 22(2): 377-394. doi: 10.22578/IJMS.22.2.23