Single-Dose SARS-CoV-2 Vaccination With BNT162b2 and AZD1222 Induce Disparate Th1 Responses and IgA Production

Abstract

While vaccination programs against SARS-CoV-2 are globally ongoing, disparate strategies for the deployment of spike antigen show varying effectiveness. In order to explore this phenomenon, we sought to compare the early immune responses against AZD1222 and BNT162b2. SARS-CoV-2 seronegative participants received a single dose of either vaccine and were analyzed for immune cell, effector T cell and antibody dynamics. AZD1222 induced transient leukopenia and major changes among innate and adaptive subpopulations. Both vaccines induced spike protein specific effector T cells which were dominated by Th1 responses following AZD1222 vaccination. A significant reduction of anti-inflammatory T cells upon re-stimulation was also restricted to AZD1222 vaccinees. While IgM and IgG were the dominant isotypes elicited by AZD1222, BNT162b2 led to a significant production of IgG and IgA. Our results suggest that the strategy for spike antigen delivery impacts on how and to what extent immune priming against the main SARS-CoV-2 antigen proceeds.

Persistence of Anti-SARS-CoV-2 Spike IgG Antibodies Following COVID-19 Vaccines

“…When two mRNA vaccines, mRNA-1273 and BNT162b2, were compared, two doses of mRNA-1273 induced higher antibody titers (GMT, 3,836 U/mL) as compared to two doses of BNT162b2 (GMT of 1,444 U/mL). 35 There might also be differences in the type of antibody responses as BNT162b2 and AZ1222 both elicited IgM and IgG, 44 BNT162b2 vaccine was reported to induce much evident IgA responses. 45 , 46 In addition, although AZ1222 vaccine elicited lower antibody responses as our data showed, it has been shown that it induces more stable antibody responses over time.…”