Vaccine candidate containing tetanus toxoid potentially protective against SARS-CoV-2 Researchers from Cuba, China, and France have demonstrated the potential of coupling a viral antigen with the tetanus toxoid protein as a vaccination approach to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – the agent that causes coronavirus disease 2019 (COVID-19). Tetanus toxoid (TT) is a chemically inactivated version of the tetanus toxin produced by the bacteria Clostridium tetani. This chemically inactivated antigen can be used as a protein carrier in vaccines to induce potent immune responses in vivo. The SARS-CoV-2 infection process is mediated by a surface structure called the spike protein. The receptor-binding (RBD) domain of this spike protein contains a receptor-binding motif (RBM) that mediates the interaction of the RBD with the host cell receptor angiotensin-converting enzyme 2 (ACE2).