CD40LG and Pleural effusion: In addition, pleural effusion (aOR, 4.792; 95% CIs, 1.549–14.820), LDH levels (aOR, 1.002; 95% CIs, 1.001–1.004), MP-specific IgM titer (aOR, 1.280; 95% CIs, 1.080–1.518), oxygen need at the time of admission (aOR, 7.628; 95% CIs, 1.764–32.986), and rhinovirus co-infection (aOR, 3.283; 95% CIs, 1.144–9.418) were significantly associated with the non-responder group.