Introduction
Korean infants born at 32?35 weeks? gestational age (wGA) receive palivizumab only if they have siblings. We assessed the impact of using additional risk factors to target respiratory syncytial virus (RSV) prophylaxis in Korea.
Methods
The impact of current birth rates on the number of siblings was explored. The ability of siblings alone vs the 3-risk factor (young age; smoking; siblings/daycare) International Risk Scoring Tool (IRST) to predict RSV-hospitalisation (RSVH) was assessed in a pooled dataset of 13,475, 32?35wGA infants.
Results
The Korean fertility rate has fallen from 1.2 in 2012 to 0.78 in 2022, with 24.9% of women aged 40?49 years now having one child. Infants? RSVH risk increased with sibling number: none=1% risk; 1-2=1.5%; ?3=5.1%. Using siblings correctly identified 60.0% of RSVHs with an area under the receiver operating characteristic curve of 0.574 (1=perfect prediction), compared to 85.2% and 0.773 with the IRST. Excluding siblings, the IRST identified infants at moderate RSVH risk with other risk factor combinations (Table).
Table: IRST risk factor combinations excluding siblings that identify moderate-risk infants
| Birth 3 months before to 2 months after season start (score 6) | One of smokers in household/ smoking while pregnant (5) |
Both smokers in household/smoking while pregnant (11) | Daycare (14) | Risk score and category |
| + | - | - | + | 20=Moderate |
| - | - | + | + | 25=Moderate |
| + | + | - | + | 25=Moderate |
| + | - | + | + | 31=Moderate |
Conclusions
Korea has an increasing rate of single child families. Siblings is an important risk factor for RSVH but lacks discriminatory power in isolation. Adoption of the IRST would avert up to 85% of potential RSVHs in this moderate to late preterm cohort.