A research group from Osaka University led by Professor Hisashi Arase and consisting of researchers from the Research Institute for Microbial Diseases, the Institute for Protein Research, the Immunology Frontier Research Center, the Center for Infectious Diseases, and the Graduate School of Medicine has discovered for the first time that both neutralizing antibodies that protect against infection as well as infection-enhancing antibodies that increase infectivity are produced after infection with SARS-CoV-2 by analyzing antibodies derived from COVID-19 patients.