Weakly positive Mycoplasma pneumoniae is not contagious. Weakly positive Mycoplasma pneumoniae refers to weakly positive antibodies to Mycoplasma pneumoniae, and does not mean that there is an acute Mycoplasma pneumoniae infection. Mycoplasma pneumoniae antibodies consist of 2 types: one is IgG and the other is IgM, of which IgG positivity merely indicates that there has been an infection with Mycoplasma pneumoniae and the body produces the corresponding antibodies, whereas IgM antibody positivity indicates that there is an acute infection, but there is still the possibility of a false-positive test, especially a weak positive test. Even if Mycoplasma pneumoniae infection is evident in the body, the contagiousness is extremely low, and Mycoplasma pneumoniae can be completely asymptomatic, i.e., carried without symptoms. Both respiratory Mycoplasma pneumoniae infections and urinary tract Mycoplasma pneumoniae infections have very low contagiousness and are not considered infectious diseases.