Study Participation
From 2011­–2016, 2576 children were enrolled in NPICS, 1269 (49.3%) were boys and 1307 (49.7%) were girls. The age distribution, enrollment, and reported sex by year are summarized in figure 1. The overall age distribution by cohort year is described in Fig. 1A. The age structure for those under 1 year old are summarized in Fig. 1B. The median age of those entering the cohort after January 2011 was five months old (IQR 0.7–29.4 months), the majority being enrolled in their first year of life (Fig. 1C). The median age of enrollees exiting the cohort was seven years (IQR 4–11 years). Study participants consistently visited the clinic throughout the study period (Supplemental Fig. 1), across the study period 24.8% of participant clinic visits (11677/47006) met the hMPV testing criteria, and 9.3% (4346/47006) met the criteria for ALRI. The loss-to-follow up throughout the study period was low ranging from 2%-5% per year and are described in detail in Supplemental Table 1.