The trial was a randomized, observer-blinded, Phase 1 study to evaluate the safety and immunogenicity of the RSV F Vaccine, with one or two doses, with or without aluminum phosphate adjuvant, in healthy pediatric participants two to six years of age. The trial's primary goal was to evaluate safety in this population and immunogenicity as measured by concentrations of serum IgG antibodies to the RSV fusion, or F-protein, palivizumab-competing antibody (PCA) titers and RSV microneutralization titers.
Of the 32 total children enrolled, serum samples were collected from a subset of 18 children in the per-protocol population at 14, 28 and 56 days. All RSV F Vaccine formulations and regimens were well-tolerated and highly immunogenic. Consistent with prior trials, anti-F IgG and PCA titers increased rapidly at day 14, peaked at day 28 and remained at elevated levels through day 56; the last time point currently analyzed. There were greater than 10-fold increases in both anti-F IgG and PCA antibody titers in the adjuvanted group and greater than 6-fold increases in anti-F IgG and PCA antibody titers in the unadjuvanted group.
“Given the seasonality of RSV and the fact that infection could confound interpretation of the data, we closed out the trial prior to the initiation of the RSV season. Despite the small population, we were able to observe that the vaccine has the potential to be both safe and immunogenic in young children,” said
“Our RSV F Vaccine has now elicited a robust immune response in all three of our target populations: older adults, infants via maternal immunization and pediatrics. We are evaluating this data in the context of our RSV F Vaccine overall clinical development program and look forward to providing an update in the next several months on our path forward in the pediatric population,” said
Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections and the leading viral cause of severe lower respiratory tract disease in infants and young children worldwide, with estimated annual infection and mortality rates of 64 million and 160,000, respectively1. In the US, RSV is the leading cause of hospitalization of infants2. Despite the induction of post-infection immunity, repeat infection and lifelong susceptibility to RSV is common3,4. Currently, there is no approved RSV vaccine available. Palivizumab is a monoclonal antibody, licensed and sold by MedImmune as Synagis®, that targets the RSV F protein and is used for prophylaxis against RSV disease in high risk infants.
1. Nair, H. et al. Global burden of acute lower respiratory infections due to respiratory syncytial virus in young children: a systematic review and meta-analysis. Lancet, 2010; 375: 1545-1555.
2. Hall, C.B. et al. Respiratory Syncytial Virus-Associated hospitalizations Among Children Less Than 24 Months of Age. Pediatrics, 2013; 132(2): E341-348.
3. Glezen, W.P. et al. Risk of primary infection and reinfection with respiratory syncytial virus. Am J Dis Child, 1986; 140:543-546.
4. Glenn GM, et al. Modeling maternal fetal RSV F vaccine induced antibody transfer in guinea pigs. Vaccine, 2015; In press. http://dx.doi.org/10.1016/j.vaccine.2015.08.039.
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