S100A8 and pneumonitis: In this study, serum S100A8/A9 levels in children infected with CAP (1.59 ± 1.32 ng/mL) were five times higher than those in healthy children (0.31 ± 0.21 ng/mL) and approximately two times higher than those in children with pneumonitis (0.79 ± 0.40 ng/mL).