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 78% of expected child-days and 68% of expected swab returns was a very good retention rate given the intensive and prolonged nature of the study for participating families. Analysis of incidence rates of ARI in participants that withdrew from the study at different periods showed no clear association between time of dropout and ARI incidence. Regular parent-collected nasal swabs avoids the need for home visits by research staff or clinic attendance during an ARI, minimising possible biased estimates of ARI events and specimen availability from losing families failing to seek healthcare. Moreover, regular weekly nasal swab collections increase the likelihood of virus detections during an ARI episode rather than relying simply on results from a single specimen. Our previous work found that with sensitive PCR techniques, parent-collected nose or nose-throat swabs sent to the laboratory by standard mail had comparable sensitivity to nasopharyngeal swabs obtained by healthcare workers. 18 19 30 Longitudinal data collection also allows assessment of asymptomatic status by considering past and future illness history, as some viruses are detectable days before and after ARI symptoms develop, 31 and are therefore less likely to yield false-positive findings.