Human memory T cell dynamics after aluminum-adjuvanted inactivated whole-virion SARS-CoV-2 vaccination

This study evaluates the functional capacity of CD4(+) and CD8(+) terminally-differentiated effector (T-EMRA), central memory (T-CM), and effector memory (T-EM) cells obtained from the volunteers vaccinated with an aluminum-adjuvanted inactivated whole-virion SARS-CoV-2 vaccine (CoronaVac). The volunteers were followed for T cell immune responses following the termination of a randomized phase III clinical trial. Seven days and four months after the second dose of the vaccine, the memory T cell subsets were collected and stimulated by autologous monocyte-derived dendritic cells (mDCs) loaded with SARS-CoV-2 spike glycoprotein S1. Compared to the placebo group, memory T cells from the vaccinated individuals significantly proliferated in response to S1-loaded mDCs. CD4(+) and CD8(+) memory T cell proliferation was detected in 86% and 78% of the vaccinated individuals, respectively. More than 73% (after a short-term) and 62% (after an intermediate-term) of the vaccinated individuals harbored T-CM and/or T-EM cells that responded to S1-loaded mDCs by secreting IFN-& gamma;. The expression of CD25, CD38, 4-1BB, PD-1, and CD107a indicated a modulation in the memory T cell subsets. Especially on day 120, PD-1 was upregulated on CD4(+) T-EMRA and T-CM, and on CD8(+) T-EM and T-CM cells; accordingly, proliferation and IFN-& gamma; secretion capacities tended to decline after 4 months. In conclusion, the combination of inactivated whole-virion particles with aluminum adjuvants possesses capacities to induce functional T cell responses.

Automated summary

This study evaluates the functional capacity of CD4(+) and CD8(+) memory T cells obtained from volunteers vaccinated with an aluminum-adjuvanted inactivated whole-virion SARS-CoV-2 vaccine. The results show that memory T cells from vaccinated individuals significantly proliferate and secrete IFN-γ in response to S1 stimulation.