Evaluation of T Cell Immune Memory Response after Sinopharm (BBIBP-CorV), Gam-COVID-Vac (Sputnik-V), and Heterologous Sputnik-V/mRNA-1273 (Moderna) COVID-19 Vaccination Schemes against Different SARS-CoV-2 Variants.

IntroductionThe adaptive immune response plays a crucial role in resolution of viral infections; however, there is limited data on the T cell response to SARS-CoV-2 vaccines like Sinopharm (Sin), Sputnik-V (SpV), and especially for the heterologous combination Sputnik-V/mRNA-1273 (Spv/Mod) scheme. Furthermore, emerging variants may compromise the adaptive immune response established in the population. ObjectiveTo evaluate the T cell immune response induced by the Sin, SpV and SpV/Mod, against Wuhan, Gamma and Omicron viral variants. MethodsSerum levels of IgG antibodies were assessed by CMIA (Abbott Diagnostics, Abbott Park, Illinois). T cell responses against Wuhan, Gamma, and Omicron were evaluated through an activation-induced marker assay. Sixty individuals, evenly distributed across the Sin, SpV, and SpV/Mod groups, were included. ResultsThe median age of participants was 48 years (IQR: 34-56), with 58.3% (n=35) being female. Seventeen (28.3%) individuals had a prior confirmed COVID-19 infection. Spv/Mod scheme elicited significantly higher humoral responses (p<0.001). However, the three vaccination platforms showed consistent T cell responses across the different Wuhan, Gamma and Omicron stimuli tested. Particularly, all three schemes induced stronger CD8 responses against the Wuhan variant. In addition, more responders to Wuhan were observed in the Sin and Spv groups, while the Spv/Mod group showed a higher proportion of responders to Omicron. ConclusionThis study provides new data on effective humoral and cellular immune responses against Wuhan, Gamma, and Omicron variants. Moreover, memory CD4 and CD8 T cell responses remain protective, and the heterologous scheme may elicit stronger T cell responses against emerging variants. HighlightsO_LIStrong adaptive T cell responses were observed across all vaccination schemes and viral variants. C_LIO_LIHigher frequency of activated CD8 lymphocytes was detected compared to CD4 in response to SARS-CoV-2 C_LIO_LISinopharm and Sputnik-V showed a response biased toward the Wuhan variant. C_LIO_LISputnik-V/Moderna recipients showed higher T cell responses to Omicron. C_LIO_LIThe Sputnik-V/Moderna vaccination scheme induced significantly enhanced humoral immune responses. C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=188 HEIGHT=200 SRC="FIGDIR/small/24318016v1_ufig1.gif" ALT="Figure 1"> View larger version (62K): org.highwire.dtl.DTLVardef@198b7ddorg.highwire.dtl.DTLVardef@14f0efcorg.highwire.dtl.DTLVardef@160ec18org.highwire.dtl.DTLVardef@2c2ab9_HPS_FORMAT_FIGEXP M_FIG C_FIG