There were three pneumonia case definitions used in the studies: I. The World Health Organization (WHO) case definition of pneumonia for Integrated Management of Childhood Illness [12] , II. Chinese medical association guidelines (IIa: communityacquired pneumonia (CAP) [13] or IIb: hospital-acquired pneumonia (HAP) [14] ), and III. physician assessment (IIIa: acute lower respiratory infection; IIIb: newborn pneumonia; or IIIc: pneumonia as a cause of death in children under 5 years of age). The specific signs and symptoms for each case definition are detailed in Table S1 .