Immunology: Promising phase I trial results for a new SARS-CoV-2 vaccine candidate

A peptide-based vaccine candidate, called CoVac-1, is shown to induce immunity against SARS-CoV-2 in a phase I clinical trial reported in Nature this week. The vaccine candidate induces T cell immunity, an important response for the control of viruses, and could be helpful for people with immunodeficiencies.

T cells have a role in fighting off pathogens, such as viruses, by either attacking infected cells or by facilitating the production of protective antibodies by B cells. T cell immunity is particularly important for individuals with B cell deficiencies, such as patients with cancer. CoVac-1 aims to induce, in a single shot, long-lasting SARS-CoV-2 T cell immunity that resembles that acquired by natural infection.

In the first clinical evaluation of CoVac-1, Juliane Walz and colleagues recruited 36 participants aged 18 to 80 years, who received a single dose of the peptide vaccine. SARS-CoV-2-specific T cell responses were observed in all participants 28 days after vaccination, effects that persisted for at least 3 months. The authors find that the vaccine-induced T cell responses surpass those induced by natural SARS-CoV-2 infection. In addition, the CoVac-1-induced T cell responses are not altered by any of the current SARS-CoV-2 variants of concern (Alpha, Beta, Gamma and Delta). A favourable safety profile and induced T cell responses in all trial participants support the ongoing evaluation of the vaccine in a phase II trial, the authors conclude.