Differential T cell immunity to SARS-CoV-2 in mRNA-1273 and BNT162b2 vaccinated individuals

Abstract

Abstract T-cell immunity to SARS-CoV-2 vaccination with either BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) mRNA vaccines was quantified through a validated ELISpot assay at various time points. The magnitude and duration of response was compared between these two vaccine cohorts alongside the anti-spike IgG response. Freshly isolated peripheral blood mononuclear cells were incubated with overlapping peptide pools covering the SARS-CoV-2 spike protein in an IFNg ELISpot assay. Donors T cell responses to spike protein were assessed where possible at pre-vaccination, post second vaccination, and at long-term follow up. Anti-Spike IgG was quantified by serum ELISA. Following the 2 dose regimens, all donors developed anti-spike T-cell responses. The median decline in T-cell response between the 2nd vaccine dose and long-term follow-up was 35.1%. At long-term follow-up, T-cell responses in BNT162b2 vaccinated individuals were lower than mRNA-1273. Median T-cell responses were 38.5 SFU/2.5×105 (BNT162b2 ) and 86 SFU/2.5×105 (mRNA-1273). Anti-spike IgG decreased by a median of 89.3% at long-term follow-up. Individuals receiving BNT162b2 had lower serum antibody levels long-term compared to mRNA-1273. The median antibody responses were 205.3 BAU/mL (BNT162b2 ) and 335 BAU/mL (mRNA-1273). Both humoral and cellular immunity to SARS-CoV-2 is decreased long-term post-vaccination with either mRNA vaccine, and both are significantly lower in BNT162b2-vaccinated compared to mRNA-1273-vaccinated individuals, with a greater magnitude of difference in the T cell response between vaccines compared to antibody levels. As breakthrough infections continue to rise, understanding the dynamics of these vaccine responses is crucial.