Phase III MATISSE trial of RSVpreF vaccine meets one primary endpoint in Respiratory Syncytial Virus

The pre-planned, interim efficacy analysis conducted by an external and independent Data Monitoring Committee (DMC) met the success criterion for one of two primary endpoints. The observed efficacy for severe medically attended lower respiratory tract illness (severe MA-LRTI) was 81.8% (CI: 40.6%, 96.3%) through the first 90 days of life. Substantial efficacy of 69.4% (CI: 44.3%, 84.1%) was demonstrated for infants over the six-month follow-up period.

Although the statistical success criterion was not met for the second primary endpoint, clinically meaningful efficacy was observed for MA-LRTI of 57.1% (CI: 14.7%, 79.8%) in infants from birth through the first 90 days of life. Efficacy for MA-LRTI of 51.3% (CI: 29.4%, 66.8%) was observed over the six-month follow up period.

Pre-planned safety reviews conducted at regular intervals throughout the duration of the study by the DMC also indicate the investigational vaccine is well-tolerated with no safety concerns for both the vaccinated individuals and their newborns. At the recommendation of the DMC, and in consultation with the U.S. Food and Drug Administration (FDA), Pfizer has stopped enrollment in the study. Based on these positive results Pfizer plans to submit a Biologics License Application (BLA) to the FDA by the end of 2022 for the vaccine candidate followed by other regulatory authorities in the coming months.