A Novel Six Consecutive Monthly Doses of Palivizumab Prophylaxis Protocol for the Prevention of Respiratory Syncytial Virus Infection in High-Risk Preterm Infants in Taiwan

BACKGROUND Respiratory syncytial virus (RSV) circulates year round in Taiwan. A novel six consecutive monthly doses of palivizumab for RSV prevention protocol has been approved for high risk preterm infants since December 2010. This study aimed to determine the clinical effectiveness and safety of this novel protocol for the prevention of RSV infection. METHODS From April 2011 to March 2013, we enrolled infants born at ≤28 weeks gestation and infants born at ≤35 weeks gestation with chronic lung disease (CLD) who received palivizumab prophylaxis as study group and followed up for 12 months. Historic control, those who were born and followed up between July 2000 and June 2008, were retrieved for propensity score matching. Primary endpoint was RSV-related hospitalization, and secondary endpoints included the length of hospital stay and intensive care unit (ICU) care. RESULTS We enrolled 127 infants (108 infants born at ≤28 weeks and 19 infants born at 29-35 weeks with CLD). They completed 6-dose palivizumab as scheduled. Among the study group, the RSV-related hospitalizations were 2 (1.6%) within 6 months and 5 (3.9%) within 12 months after discharge. We matched 127 infants in the control group with 127 infants in the study group by propensity score matching. The reduction of RSV-related hospitalization rates were 86% (10.2% vs 1.6%, p = 0.002) within 6 months after discharge and 78% (15.7% vs 3.9%, p = 0.004) within 12 months after discharge. Compared to the control group, the rate of ICU care significantly decreased from 7.1% to 0.8% (p = 0.024) within 6 months after discharge and from 7.9% to 0.8% (p = 0.014) within 12 months after discharge. Adverse events were recorded in 6.4% injections. CONCLUSIONS Six monthly intramuscular administration of palivizumab is effective for prevention of RSV hospitalization in regions with no single seasonal peak of RSV infection such as Taiwan.