Six-monthly palivizumab prophylaxis effectively reduced RSV-associated hospitalization rates of preterm infants in a subtropical area: a population-based cohort study

Background: To evaluate the effects of 6-monthly palivizumab on respiratory syncytial virus-associated hospitalization (RSVH) in preterm infants in an area without RSV seasonality. Methods: RSV prophylaxis with 6-monthly palivizumab in infants born at gestational age (GA) ≤28 weeks or those born at GA 29–35 weeks with bronchopulmonary dysplasia (BPD) was implemented in Taiwan since 2010. RSVH, use of mechanical ventilation (MV), admission to intensive care unit (ICU), length of hospital stay, and annual mortality were compared between the historical control group (no prophylaxis, 2008–2009) and the prophylaxis group (2011–2013). Results: The annual RSVH rates decreased in the target population and in subgroups of infants who received prophylaxis (all target infants: odds ratio [OR], 0.43; 95% confidence interval [CI], 0.29–0.65). No difference was observed in MV and ICU usage and 1-year mortality in the ≤28 weeks subgroup. In the GA 29–35 weeks with BPD subgroup, ICU usage and 1-year mortality rates were significantly reduced with palivizumab prophylaxis regimen. A significant decrease was noted in the annual mortality and ICU admission rates of infants who received prophylactic treatment. Conclusion: Six-monthly palivizumab treatment reduced the RSVH rate, ICU usage, and annual mortality rates of target infants in an area without RSV seasonality.