Table 1.

Panel

Study definitions
Cases
WHO severe pneumonia	Cough and/or difficult breathing with lower chest indrawing and no WHO danger signs
WHO very severe pneumonia	Cough and/or difficult breathing with at least one danger sign (central cyanosis, difficulty breastfeeding or drinking, vomiting everything, convulsions, lethargy, or unconsciousness, head nodding)
Controls
ARI control	Cough or runny nose reported or if (A) ear discharge, wheeze or difficulty breathing and (B) either fever (temperature >38.0°C or reported fever in the past 48 hours) or sore throat were reported.
Non-ARI control	Does not meet definition of case or ARI control.
Lung sounds	Description	Inspiration	Expiration
Normal	Soft, not musical	Throughout	Early only
Crackle	Short, explosive, not musical, popping; usually repetitive	Primarily (but can be variable)	Less common and usually with inspiratory crackles
Wheeze	Musical, long duration; can be high or low pitch	Possible	Primarily, prolonged
Uninterpretable	Persistent crying or poor quality such that no full breath sounds are heard	Yes	Yes
Upper airway noises, not stridor	Generally louder at cheek, may mimic a low pitch wheeze or have ‘snorting’ quality similar to a crackle, can also be a vocalisation	Possible	Possible
Upper airway noises, primarily stridor	Generally louder at cheek, may mimic high pitched wheeze although is typically inspiratory only	Primarily	Possible, but less common

ARI, acute respiratory illness.