Fig. 2

Distribution of anti-spike receptor-binding domain IgG titer (in natural logarithmic scale) by anti-nucleocapsid protein (IgM and IgG), history of COVID-19 diagnosis, and vaccination status. Group 1: history of COVID-19 diagnosis, complete vaccination; Group 2: history of COVID-19 diagnosis, incomplete vaccination; Group 3: no history of COVID-19 diagnosis, complete vaccination; Group 4: no history of COVID-19 diagnosis, incomplete vaccination, thick dot and whiskers denote group mean ± SD