Effectiveness of Palivizumab Against Respiratory Syncytial Virus Hospitalization Among Preterm Infants in a Setting With Year-Round Circulation

Abstract

Abstract Background The year-round respiratory syncytial virus (RSV) circulation in tropical regions leads to different transmission patterns and burden of disease among infants born very preterm. Methods We conducted a retrospective cohort study to estimate the effectiveness of palivizumab in preventing RSV hospitalization at 6 and 12 months after discharge, among infants born at <32 weeks’ gestation in our tropical setting. Results A total of 109 infants (26.3%) received palivizumab at discharge, of 415 who were eligible. All patients received ≥4 doses, with 105 infants (96.3%) completing 5 doses. Within 1 year after discharge, there were 35 RSV-associated admissions (3 [2.8%] in the palivizumab vs 32 [10.5%] in the nonpalivizumab group; P = .02). After adjustment for confounders, the effectiveness of palivizumab against RSV hospitalization was estimated to be 90% (95% confidence interval, 10%–99%) up to 6 months after discharge. The median time to RSV hospitalization was shorter in the nonpalivizumab than in the palivizumab group (median [range], 155 [15–358] vs 287 [145–359] days, respectively; P = .11). Five infants (14.3%), all from the nonpalivizumab group, required admission to the intensive care unit. Conclusions In our setting with year-round RSV circulation, palivizumab prophylaxis was effective in reducing RSV hospitalization among high-risk preterm infants of <32 weeks’ gestation within the initial 6 months after discharge.