Following the release of additional Phase III clinical trial (Prepare) data of Novavax’s ResVax, presented at the World Vaccine Congress in Washington, D.C., Paul Jeng, Senior Pharma Analyst at GlobalData, a leading data and analytics company, discusses what the results mean for Novavax’s maternal RSV vaccine:

“Despite the stated commitment from Novavax to continue commercialization efforts for ResVax, the additional data are not substantially more encouraging for ResVax’s prospects as a maternal vaccine. The top-line results from the Prepare trial released earlier this year showed that ResVax had 39% efficacy in preventing medically significant RSV-associated lower respiratory tract infections (LRTI), missing its primary endpoint. There is evidence that vaccinating earlier in gestation (<33 weeks) may have a positive impact on efficacy, but further clinical testing would be needed to expand the patient population to pregnancies earlier than 28 weeks.

“The most encouraging results came from expanded safety data, indicating no negative impact of maternal immunization on all forms of adverse events for either maternal or infant subjects. ResVax also met its secondary endpoints, reducing all-cause LRTI hospitalizations by 25.3% and all-cause LRTI hypoxemia by 39.1%. Regulatory authorities will need to determine if the safety and success of ResVax in mitigating certain severe outcomes of RSV infection are enough to warrant its licensure.

“Key opinion leaders interviewed by GlobalData have pointed to vaccine antigen selection as a possible limiting factor to the immunogenicity of ResVax. Prior to the completion of this study, there were already concerns stemming from a previously failed trial with ResVax to protect elderly adults from RSV-associated LRTI.”