Aetiological role of common respiratory viruses in acute lower respiratory infections in children under five years: A systematic review and meta–analysis

Shi, Ting; McLean, Kenneth; Campbell, Harry; Nair, Harish

We used "ALRI" as an equivalent to clinical pneumonia as our case definition, which also included bronchiolitis. This was to recognise this common manifestation in young children with viral ALRI [10] , and the limits of the WHO case definition to reliably differentiate these [1] . ALRI was characterized as cough or dyspnoea with age-related tachypnoea, while severe ALRI was defined as those with cough or dyspnoea with indrawing of the lower chest wall [11] , or an acute respiratory infection severe enough to necessitate hospitalisation. The control groups were defined as asymptomatic (with no respiratory symptoms), healthy (asymptomatic with no other symptoms) or upper respiratory tract infection (URTI) (with respiratory symptoms).