Doctor International St. Mary’s Hospital, College of Medicine, Catholic Kwandong University Seoul, Seoul-t'ukpyolsi, Republic of Korea
Abstract Text: Evaluation of the longitudinal immune responses induced by various SARS-CoV-2 vaccination regimens is still lacking. We aimed to investigate the cellular immunities in uninfected immunocompetent after different COVID-19 vaccinations. SARS-CoV-2 specific T cell responses were evaluated using 309 serial samples from 53 vaccinated healthcare workers (35 AZD1222/BNT162b2, 11 mRNA-1273, 7 Ad26.COV2.S). INF-γ enzyme-linked immunospot (ELISpot) and two commercial INF-γ release assays (QuantiFERON SARS-CoV-2, Covi-FERON) were used. The highest levels of SARS-CoV-2 specific T cell immunity were detected at 8 weeks after 2nd mRNA-1273 vaccination (mean 312.0 spots/106 PBMC), and after 4 weeks from booster shot (mean 329.3 spots/106 PBMC). The AZD1222 vaccine showed the highest level at 4 weeks after the first vaccination (mean 142.8 spots/106 PBMC), while Ad26.COV2.S showed peak response at 8 weeks after vaccination (mean 64.6 spots/106 PBMC). QuantiFERON showed a higher level of IFN-γ at 4-8 weeks after the mRNA-1273 2nd vaccination. Covi-FERON showed an increased IFN-γ level at 4 weeks after the mRNA-1273 2nd shot and after the booster shot. AZD1222 induced increased IFN-γ until 12 weeks after 2nd vaccination, and after the BNT162b2 booster shot. Ad26.COV2.S showed a continuously increased level up to 12 weeks after vaccination. Strong correlations were shown between two INF-γ release assays, whereas ELISpot showed weak correlations with INF-γ release assays. All of ELISpot, QuantiFERON and Covi-FERON showed significantly higher median results as the neutralizing antibody response increased (all P < 0.05). We found a slightly different SARS-CoV-2 specific T cell response was observed depending on the vaccines.
