Although it is still controversial regarding whether bDMARDs/tsDMARDs increase the risk of infectious diseases [1, 2], a study of side effects in RA patients treated with TNF inhibitors in Japan showed that their risk of serious infection was higher compared to the non-TNF inhibitor treatment group (odds ratio 2.37; 95% confidence interval (CI) 1.11–5.05) [3]. Here, TNF is linked to infectious disease.