COVID-19 Reinfection in the Face of a Detectable Antibody Titer

Coronavirus disease 2019 (COVID-19) reinfections are now reported from many countries with different coronavirus strains. Detectable immunoglobulin G (IgG) levels are thought to impart protective immunity to reinfection in that individual. Here, we discuss a case report of a young, healthy, type 2 diabetic patient who suffered reinfection even after four times upper normal circulating IgG antibody specific to a COVID-19 spike protein. The first time was a clinical diagnosis when he self-isolated himself and was diagnosed later by COVID-19-specific symptoms with severe acute respiratory syndrome coronavirus 2 (SARS-COV-2)-specific IgG antibody titer.