Table 1.

Case Definitions Used in the Study for RSV-LRTI

	WHO 2015 [12]	Protocol (Current Study)	Nokes et al. (2008) [18]	Exploratory
RSV-LRTI	▪ Child with history of cough or difficulty breathing	▪ Child with history of cough or runny nose or blocked nose	▪ Child with history of cough or difficulty breathing	▪ Child with history of cough or difficulty breathing
	▪ SpO2 <95% or RR increase	▪ SpO2 <95% or RR increase	▪ SpO2 <90% accompanied by clinical diagnosis of LRTI/bronchiolitis, or RR increase, or lower chest wall indrawing	▪ SpO2 <95%, or RR increase, or lower chest wall indrawing
	▪ RSV-positive by RT-qPCR	▪ RSV-positive by RT-qPCR	▪ RSV-positive by RT-qPCR	▪ RSV-positive by RT-qPCR
Severe RSV-LRTI	▪ Child with RSV-LRTI	▪ Child with RSV-LRTI	▪ Child with RSV-LRTI	▪ Child with RSV-LRTI
	▪ SpO2 <93% or lower chest wall indrawing	▪ SpO2 <92%, or difficulty breathing (leading to irritability/agitation or lethargy/sleepiness), or lower chest wall indrawing, or reduced/no vocalization, or apnea >20 seconds, or cyanosis, or stop feeding well/dehydration	▪ At least one of the following: SpO2<90% accompanied by clinical diagnosis of LRTI/bronchiolitis or lower chest wall indrawing	▪ SpO2 <93%

Abbreviations: LRTI, lower respiratory tract infection; RR, respiratory rate; RSV, respiratory syncytial virus; RT-qPCR, reverse transcription-quantitative polymerase chain reaction; SpO₂, saturation of peripheral oxygen; WHO, World Health Organization.

Notes: RR increase was defined as ≥60/min (<2 months of age); ≥50/min (2–11 months of age); ≥40/min (12–24 months of age). RR, SpO₂, and clinical symptoms were recorded by study staff at in-person visits conducted within 72 h from the identification of a new or worsened suspected LRTI case through active or passive surveillance.