Palivizumab appears to be effective for reducing respiratory syncytial virus (RSV) in high-risk infants, according to results of a study in Australia. Researchers conducted a retrospective birth cohort study of more than 23,000 high-risk infants admitted to neonatal intensive care units who were born from 2002 to 2013 with follow-up to 2015. To address confounding by indication in the cohort study (ie, that palivizumab was targeted to those at greatest risk of RSV), researchers supplemented this analysis with a self-controlled case series (SCCS) study.
In the cohort group, 1.1% of the infants received at least 1 dose of palivizumab, with use increasing over time. The number of doses ranged from 1 to 15, and more than 90% of them were administered to infants aged younger than 12 months. Overall, there were 1689 positive RSV tests before the age of 2 years, representing 1506 infants (6.2%) with at least 1 RSV detection before age 2 years. More than 10% of these infants also had another episode of RSV detection before their second birthday. Overall, receiving palivizumab was not associated with lower risk of RSV detection before age 2 years.
However, results of the SCCS study, which accounted for confounding by indication and focused on 1506 infants with 1 or more RSV detections who had at least 1 dose of palivizumab, were different. The incidence of RSV detection before age 2 years was 70% lower in the 28 days after the first dose of palivizumab than it was in control periods, and the rate of RSV detections was reduced by 74% in the 28 days after any dose (Moore HC, et al. J Pediatr. 2019; 214:121.e1-127.e1).
Thoughts from Dr Farber
I have never been completely convinced that palivizumab is worth the cost, yet I prescribe it. This study, although hardly conclusive, makes me feel better about giving it.