Burden of respiratory syncytial virus hospitalisation among infants born at 32-35 weeks' gestational age in the Northern Hemisphere: pooled analysis of seven studies.

To provide comprehensive information on the epidemiology and burden of respiratory syncytial virus hospitalisation (RSVH) in preterm infants, a pooled analysis was undertaken of seven multicentre, prospective, observational studies from across the Northern Hemisphere (2000-2014). Data from all 320-356 weeks' gestational age (wGA) infants without comorbidity were analysed. RSVH occurred in 534/14 504 (3.7%) infants; equating to a rate of 5.65 per 100 patient-seasons, with the rate in individual wGA groups dependent upon exposure time (P = 0.032). Most RSVHs (60.1%) occurred in December-January. Median age at RSVH was 88 days (interquartile range (IQR): 54-159). Respiratory support was required by 82.0% of infants: oxygen in 70.4% (median 4 (IQR: 2-6) days); non-invasive ventilation in 19.3% (median 3 (IQR: 2-5) days); and mechanical ventilation in 10.2% (median 5 (IQR: 3-7) days). Intensive care unit admission was required by 17.9% of infants (median 6 days (IQR: 2-8) days). Median overall hospital length of stay (LOS) was 5 (IQR: 3-8) days. Hospital resource use was similar across wGA groups except for overall LOS, which was shortest in those born 35 wGA (median 3 vs. 4-6 days for 32-34 wGA; P < 0.001). Strategies to reduce the burden of RSVH in otherwise healthy 32-35 wGA infants are indicated.