Outcomes related to respiratory syncytial virus with an abbreviated palivizumab regimen in children with congenital heart disease: a descriptive analysis

Background It has been hypothesized that 4 doses of palivizumab, a neutralizing monoclonal antibody against respiratory syncytial virus (RSV), administered during a fixed-date RSV season may reduce hospital admissions comparably to the standard 5-dose schedule. We report outcomes in children with congenital heart disease approved to receive this 4-dose palivizumab schedule in British Columbia. Methods We performed a population-based descriptive cohort analysis of all 406 approved palivizumab courses over 4 seasons (2012/13 to 2015/16) in 325 children with hemodynamically significant congenital heart disease enrolled in the British Columbia RSV Immunoprophylaxis Program. The primary outcome was in-season hospital admission for potential RSV-related lower respiratory tract infection (LRTI). Secondary outcomes include timing of admission in relation to dosing. Analysis was by intention-to-treat. Results Of the 406 approved palivizumab courses, 391 were administered. In 33 cases (8.4%), an additional dose was given immediately after cardiac bypass surgery. There were 17 RSV-confirmed hospital admissions (median age of children 5.9 mo [interquartile range 4-10 mo]) and 8 admissions in which the child was not tested for RSV, for a maximum of 25 potential RSV-related admissions (6.2 per 100 approvals [95% confidence interval 4.0-9.0]). Twenty-four (96%) of the 25 admissions occurred within the 4-dose palivizumab dosing period, and the remaining admission occurred 52 days after the fourth dose. Sixty-four (72%) of 89 admissions were RSV-negative; the baseline clinical characteristics of these children were not different from those of children with RSV-confirmed admissions. Interpretation In infants with hemodynamically significant congenital heart disease, a 4-dose fixed-date palivizumab schedule over a 6-month season provided seasonal protection comparable to that in a clinical trial involving a standard 5-dose schedule. Because RSV was responsible for only 19% of admissions for LRTI in our cohort, it is critical to continue to emphasize other preventive measures, including family education toward proper hand hygiene, breast-feeding and limiting infectious exposures in children at high risk.