Background All babies born in Ireland at ⩽30 weeks are vaccinated with synagis against bronchiolitis. Bronchiolitis can be severe and is associated with respiratory morbidity. There may be a need to use synagis beyond this age group should it prove effective.

Objectives To determine the efficacy of synagis in reducing admissions with respiratory syncytial virus (RSV)-positive bronchiolitis in infants given the vaccine and to address the need to vaccinate babies beyond 30 weeks if synagis proves effective.

Method Retrospective chart review of all RSV-positive bronchiolitis babies born at 36 weeks or less between 1999 and 2006 who were admitted to Our Lady’s Hospital for Sick Children, Ireland.

Results 49 babies were admitted. 30 were male. 81% were admitted in winter. 49% were <6 months on admission. 17 (35%) were 30 weeks or less, 49% were moderately premature (30–34 weeks). Severe bronchiolitis was seen in 18 patients (36%), nine were 30 weeks or less. 18 infants required O₂. Six infants (12%) were admitted to the intensive care unit; two (4%) were 30 weeks or less. Three infants (6%) (30–34 weeks) were ventilated. Among a variety of co-morbidities, respiratory co-morbidity was the commonest and was seen in 34 infants (69%). Bronchopulmonary dysplasia was seen in eight infants (16%). Neurological morbidity was seen in seven infants (14%). Only 17 infants (30 weeks or less) (35% of the sample size) were admitted with RSV-positive bronchiolitis despite synagis vaccine. Nine were severe. Most of the admissions (24 infants) (49%) were moderately premature babies (30–34 weeks).

Conclusion Synagis is effective in reducing infant admissions with RSV-positive bronchiolitis; however, it does not reduce severity. Moderately premature babies presented the majority of admissions in this study. Therefore, whether to vaccinate babies born beyond 30 weeks with synagis against bronchiolitis requires further studies.