Viruses causing lower respiratory symptoms in young children: findings from the ORChID birth cohort

Sarna, Mohinder; Lambert, Stephen B; Sloots, Theo P; Whiley, David M; Alsaleh, Asma; Mhango, Lebogang; Bialasiewicz, Seweryn; Wang, David; Nissen, Michael D; Grimwood, Keith; Ware, Robert S

The attributable fraction in the exposed (AFE) provides information about the percentage of cases among exposed individuals that can be attributed to the exposure. In our study, the AFE measures the percentage of ARIs in virus-positive children attributable to that particular virus. The AFE does not inform on the aetiology at an individual level, but is a key population-level metric for interpreting positive specimen results. It assists with estimation of the true burden of disease, thus guiding preventative strategies for respiratory infections, such as immunisation. Virus-specific AFE estimates for ARI in children are reported infrequently, with most studies reporting AFEs having important methodological limitations. Except for one community