Use of palivizumab in neonates who do not meet the American Academy of Pediatrics Guidelines for respiratory syncytial virus prophylaxis

Background: AAP and Italian Neonatology Society (SIN) recommend palivizumab (PVZ) prophylaxis in infants at high-risk for severe RSV infection. We evaluated safety, effectiveness and compliance to PVZ program in neonates at increased RSV risk but who did not qualify for prophylaxis according to AAP–SIN Guidelines. Methods: Retrospective, 8-year cohort study from a large tertiary Italian NICU. RSV hospitalizations, adverse events, and compliance to prophylaxis program were compared between infants who qualified for PVZ according to AAP–SIN guidelines (GroupA, n  = 461) and infants at increased risk of severe RSV disease for various underlying chronic diseases/conditions, and who received off-label, compassionate PVZ outside of guidelines (GroupB, n  = 51). Results: GroupB included infants with inherited chromosomal syndromes ( n  = 6: partial chromosomic translocations, Poland, Cornelia DeLange syndromes); Down syndrome ( n  = 7); cystic fibrosis ( n  = 1); congenital neuromuscular disorders ( n  = 7: Steinert, Werdnig–Hoffman, Thomsen diseases [three were oxygen-dependent, two had tracheostomy); severe laryngomalacia with recurrent apnoea ( n  = 4); severe gastroesophageal reflux ( n  = 5: three were under 24-hour-monitoring for prior ALTE episodes); diaphragmatic herniation after surgery ( n  = 3); cerebral palsy with recurrent apnoeas ( n  = 6); severe immunity defects/inherited immunity disorders ( n  = 4: congenital HIV infection [two], DiGeorge, Wiskott–Aldrich syndromes [one each]); and infants > 33 weeks g.a. but severely SGA ( n  = 8: mean birth-weight = 945 g [± 380]). PVZ administration was safe and well tolerated; no adverse events were reported. Compliance to enrolment was high and similar (92% in A vs.100% in B; p  = 0.15); however, the proportion of enrolled infants who completed the scheduled courses was significantly higher in B than in A (96.1% vs. 86.0%; p  = 0.03). The overall rate of RSV-related hospitalizations was very low (2.1%), and similar in both groups (2.2% in A vs. 2.0% in B; p  = 0.99). Conclusions: Palivizumab is safe in vulnerable infants at high-risk of severe RSV infections but who fall outside of the current prophylaxis guidelines. Compliance with palivizumab prophylaxis programs is high among infants with underlying chronic diseases. Table 1 . Results. All infants ( n  = 512) Group A ( n  = 461) Group B ( n  = 51) p -value Mean gestational age (weeks, m ± sd) 31.0 (± 5.8) 29.0 (± 4.8) 36.1 (± 2.2) Age at first dose (months, m ± sd) 5.2 (± 4) 5.4 (± 4) 4.2 (± 4) 0.18 Mean number of administered doses (per infant and per year) (m ± sd) 4.4 (± 2.1) 4.3 (± 2.2) 4.9 (± 1.8) 0.25 Years of prophylaxis per infant (Md) 1.2 (1) 1.0 (1) 1.5 (1) 0.08 Compliance to enrolment 93.6% 92.1% 100% 0.12 Proportion of enrolled infants who completed the scheduled courses 89.5% 86.0% 96.1% 0.03 RSV-related hospitalizations 11/512 (2.1%) 10/461 (2.2%) 1/51 (2.0%) 0.99 Mean duration of stay in hospital, and (range) 5.4 (2–10) 6 (2–10) 7 0.33