The video provides a simplified explanation of the infection mechanism of SARS-CoV-2 in epithelial cells, as well as the importance of the ACE2 cellular receptor and the RBD domain of the viral spike protein. It also describes the design and production of the antigen used in the COVID-19 vaccine developed by HIPRA, which is based on a dimer composed of two RBD domain sequences. This approach allows the generation of either bivalent or monovalent antigens, and explores the potential implications for the diversity of antibodies that may be induced through immunization with RBD heterodimers or homodimers.