Long-term efficacy of the peptide-based COVID-19 T cell activator CoVac-1 in healthy adults.

Objectives: T cell immunity is key for the control of viral infections including SARS-CoV-2, in particular with regard to immune memory and protection against arising genetic variants.
Methods: We recently evaluated a peptide-based SARS-CoV-2 T cell activator termed CoVac-1 in a first-in-human trial in healthy adults. Here, we report on long-term safety and efficacy data of CoVac-1 until month 12.
Results: CoVac-1 is well tolerated without long-term immune-related side effects and induces long-lasting anti-viral T cell responses in 100% of study participants, with potent expandability of clusters of differentiation (CD4 ⁺ ) and CD8 ⁺ T cells targeting multiple different CoVac-1 T cell epitopes. T cell responses were associated with stronger injection site reaction. Beyond induction of T cell immunity, 89% of subjects developed CoVac-1-specific immunoglobulin G antibodies which associated with the intensity of the T cell response, indicating that CoVac-1-specific CD4 ⁺ T cells support the induction of B-cell responses. Vaccination with approved COVID-19 vaccines boosted CoVac-1-specific T cell responses. Overall, a low SARS-CoV-2 infection rate (8.3%) was observed.
Conclusion: Together, a single application of CoVac-1 elicits long-lived and broad SARS-CoV-2-specific T cell immunity, which further supports the current evaluation of our T cell activator in patients with congenital or acquired B-cell defects.
Competing Interests: Declarations of Competing Interest JSH, HRS, H-GR, and JSW are listed as inventors on a patent (EP 20 169 047.6) related to the SARS-CoV-2 T cell epitopes included in CoVac-1. H-GR and K-HW are listed as inventors on a patent related to the adjuvant XS15 included in CoVac-1 (DE102016005550.2). The other authors declare no competing interests.
(Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)