CD40LG and Pleural effusion: Pleural effusion (aOR, 5.127; 95% CIs, 1.404–18.727), respiratory virus co-infection (aOR, 4.354; 95% CIs, 1.374–13.800), LDH levels (aOR, 1.005; 95% CIs, 1.002–1.007), and MP-specific IgM titer (aOR, 1.309; 95% CIs, 1.095–1.564) at the time of admission were associated with increased risk of no response or progression of MP pneumonia when the good response group was considered as the reference group.