Characteristics of the cohort
During the study period 1719 infants were born at the HFME. Cord bloods were available for 1574 of them. Because it was not financially feasible to test all samples, two days, every two months, were allocated to process study samples, and then 578 were randomly included for analysis. Among those included, there were 71 infants aged 0-3 months who visited the emergency department with a diagnosis of LRTI and 43 hospitalized with a diagnosis of VS-LRTI; of the latter, 36 tested positive for RSV (Fig. 1).
The total cohort comprised 578 infants; 53.8% (n=311) were boys, 6.1% (n=35) from multiple births, 23.0% (n=133) born by cesarean section, from 60.7% (n=351) multiparous mothers, 9.9% (n=57) born preterm, and the mean (SD) birth weight was 3179 (633) g. Among the 36 hospitalized in their first 3 months of life with a laboratory-confirmed RSV VS-LRTI infection, 50.0% (n=18) were boys, none were premature, 88.9% (n=32) were born to multiparous mothers, and none were from multiple births (Table 1).