Enrollment for Novovax’s Phase 3 clinical trial of its RSV F vaccine has reached approximately 4,600 participants, of whom, at least 3,000 have received the vaccine.

RSV F is a respiratory syncytial virus F protein recombinant nanoparticle vaccine for infants via maternal immunization.

The Prepare Phase 3 clinical trial is testing the vaccine in healthy, third trimester pregnant women. The primary objective is to determine the efficacy of maternal immunization with the RSV F Vaccine against medically significant RSV-positive lower respiratory tract infection (LRTI) in infants through a minimum of the first 90 days of life and up through the first six months of life.

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, respectively. In the US, RSV is the leading cause of hospitalization of infants.

“RSV remains an urgent global unmet medical need due to the mortality and morbidity associated with RSV disease in infants and the absence of a vaccine to prevent such disease. We look forward to completing the interim analysis of the Prepare trial as this is the next step on the path to filing marketing applications in the US and Europe for the first-ever RSV vaccine,” said Stanley C. Erck, president and CEO of Novavax.

The Prepare trial is supported by a grant of up to $89.1 million from the Bill & Melinda Gates Fund. This grant supports development activities, product licensing efforts and World Health Organization prequalification of the RSV F Vaccine.