Novavax Continues Phase 3 Trial of the RSV F Vaccine for Infants via Maternal Immunization and Provides Update on Phase 1/2 Trial of the NanoFlu(TM) Vaccine

• RSV F Vaccine informational analysis completed in fourth quarter of 2017
• RSV F Vaccine interim analysis expected mid-2018 with approximately 4,600 enrollees
• Filing of RSV F Vaccine BLA anticipated by late 2019
• NanoFlu Vaccine data package to be completed and released in February 2018

GAITHERSBURG, Md., Dec. 18, 2017 (GLOBE NEWSWIRE) -- Novavax, Inc. (Nasdaq:NVAX) today announced the Phase 3 trial of its RSV F protein recombinant nanoparticle vaccine (RSV F Vaccine) for infants via maternal immunization will continue. Novavax also provided an update on its nanoparticle influenza vaccine candidate with proprietary Matrix-M(TM) adjuvant (NanoFlu(TM)).

RSV F Vaccine for Infants via Maternal Immunization

"Novavax has completed an informational analysis of our Phase 3 trial of the RSV F Vaccine for infants via maternal immunization using threshold criteria for a commercial product. As a result, we are accelerating our Phase 3 trial enrollment into 2018. Our maternal immunization program is supported by an $89 million grant from the Bill and Melinda Gates Foundation and has also been granted Fast Track designation by the U.S. Food and Drug Administration," said Stanley C. Erck, President and CEO. "We have enrolled over 3,000 volunteers to date and anticipate that the current pace of enrollment would trigger an interim analysis in mid-2018, with an expected Phase 3 primary endpoint readout in early 2019. This timing would allow us to submit a biologics license application (BLA) by the end of 2019."

NanoFlu Vaccine

A number of key scientific developments regarding influenza vaccines for the current season have occurred and relate to our NanoFlu program, including:

• A November 29, 2017, editorial in the New England Journal of Medicine¹ detailed public health concerns related to the poor efficacy of existing seasonal influenza vaccines that is due, in part, to genetic changes or drift in the hemagglutinin (HA) protein, leading to low vaccine efficacy
• Based on analyses from the Southern Hemisphere, the effectiveness of the seasonal influenza vaccine was as low as 10% for the A(H3N2) strain²
• A November 6, 2017, Proceedings of the National Academy of Sciences³ publication identified that the circulating influenza A(H3N2) virus contains an HA structure that has been lost in the corresponding vaccine strain during adaptation to be grown in eggs ("egg-adapted") as part of the typical seasonal influenza vaccine manufacturing process, which, in turn, affects vaccine efficacy for egg-based vaccines
• Novavax' NanoFlu vaccine candidate is designed specifically to address these challenges
• The wild-type viruses necessary to assess immunogenicity of the vaccines to circulating strains have been difficult to obtain, grow and maintain genetic stability
• Therefore, a complete Phase 1/2 data package expected in February 2018

"Recent information published presents both an opportunity and a challenge for our NanoFlu Vaccine program. First, we have the unique opportunity to determine whether our recombinant, adjuvanted NanoFlu vaccine can address egg-adapted virus mismatch. We can also observe whether our vaccine-induced antibodies can neutralize circulating viruses with antigenic drift in humans, as we demonstrated in our ferret study earlier this year," said Greg Glenn, M.D., President, R&D. "Our team has been able to optimize our assays to address this challenge and we expect to present NanoFlu immunogenicity data that includes HA inhibition and microneutralization assays comparing wild-type virus and egg-based reagents."