This cryo-EM structure of RBD-chAbs and S protein suggested that RBD-chAb-15 and -45 could be useful as a cocktail therapy for COVID-19, and we demonstrated that the cocktail of RBD-chAbs exhibited good neutralizing capability with low IC50 values in SARS-CoV-2 variant pseudovirus neutralizing experiments. The gene discussed is PROS1; the disease is COVID-19.