Clinical Stage Pipeline

Clinical Pipeline

Our product pipeline includes vaccine candidates engineered to elicit differentiated immune responses with the potential to provide increased protection. Our nanoparticle technology targets antigens with conserved epitopes essential for viral function. Unlike traditional vaccines that ‘mimic’ viruses and elicit naturally occurring immune responses to them, our nanoparticles are engineered to elicit differentiated immune responses, which may be more efficacious than naturally-occurring immunity. Our vaccine technology has the potential to be applied broadly to a wide variety of human infectious diseases.

Respiratory Syncytial Virus F-protein nanoparticle vaccine candidate (RSV F Vaccine)

We are developing our respiratory syncytial virus fusion (F) protein nanoparticle vaccine candidate (RSV F Vaccine) for three susceptible target populations: infants via maternal immunization, older adults (60 years of age and older) and children six months to five years of age (pediatrics). We believe our RSV F Vaccine represents a multi-billion dollar commercial opportunity. Currently, there is no approved RSV vaccine available.

Repeat infections and lifelong susceptibility to RSV are common and we currently estimate the annual global cost burden of RSV to be in excess of $88 billion. Despite decades of effort to develop an RSV vaccine, there are currently no licensed vaccines. Although the monoclonal antibody palivizumab (Synagis®) is indicated for the prevention of serious lower respiratory tract disease caused by RSV in children at high risk of RSV disease, it is not indicated for use in other populations. We made a breakthrough in developing a vaccine that targets the fusion protein, or F-protein, of the RSV virus. The F-protein has highly conserved amino acid sequences, called antigenic sites, which we believe are ideal vaccine targets. Palivizumab, which also targets antigenic site II, has demonstrated protection in five randomized clinical trials.

We genetically engineered a novel F-protein antigen resulting in enhanced immunogenicity by exposing these antigenic sites. The Novavax RSV F Vaccine assembles into a recombinant protein nanoparticle optimized for F-protein antigen presentation. We are seeking to bring the first RSV vaccine to market to combat the 64 million RSV infections that occur globally each year. [1],[2]

NOVAVAX’ maternal immunization
RSV vaccine candidate

ResVax - RSV F Vaccine - Infants via Maternal Immunization

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.[5] In the U.S., RSV is the leading cause of hospitalization of infants, and globally, is second only to malaria as a cause of death in children under one year of age.[6],[7] Despite the induction of post-infection immunity, repeat infection and lifelong susceptibility to RSV is common.[8],[9]

We initiated Prepare, a global pivotal Phase 3 clinical trial of our RSV F Vaccine, in 5,000 to 8,255 healthy pregnant women in December 2015. The primary objective of the Prepare trial is to determine the efficacy of maternal immunization with the RSV F Vaccine against symptomatic RSV lower respiratory tract infection with hypoxemia in infants through a minimum of the first 90 days of life. This Phase 3 trial utilizes a group sequential design and is expected to take four years to complete.

The Phase 3 trial is supported by a grant of up to $89.1 million from BMGF. The grant supports development activities, product licensing efforts and World Health Organization (WHO) prequalification of our RSV F Vaccine. In 2015, along with the Grant agreement, we concurrently entered into a Global Access Commitments Agreement (GACA) with BMGF, under which we agreed to make the RSV F Vaccine available and accessible at affordable pricing to people in certain low and middle income countries.

In September 2015, we announced positive top-line data from a Phase 2 clinical trial of our RSV F Vaccine in 50 healthy pregnant women and their infants. This clinical trial evaluated the safety and immunogenicity of our RSV F Vaccine in pregnant women in their third trimester, and assessed the transplacental transfer of maternal antibodies induced by the vaccine. The trial also examined the impact of maternal immunization on infant safety during the first year of life and RSV-specific antibody levels through the infants’ first six months of life. Immunized women demonstrated a geometric mean 14-fold rise in anti-F IgG, 29-fold rise in palivizumab-competing antibodies and a 2.7 and 2.1-fold rise in microneutralization titers against RSV/A and RSV/B respectively. In contrast, women who received placebo demonstrated no significant change in antibody levels. The infants’ antibody levels at delivery averaged 90-100% of the mothers’ levels, indicating efficient transplacental transfer of antibodies from mother to infant. The estimated half-lives of infant PCA, anti-F IgG, RSV/A and RSV/B microneutralizing antibodies, based on data through day 60, were 41, 30, 36 and 34 days, respectively.

In November 2014, the U.S. Food and Drug Administration, Center for Biologics Evaluation and Research (FDA) granted Fast Track designation to our RSV F Vaccine for protection of infants via maternal immunization. Fast Track designation is intended for products that treat serious or life-threatening diseases or conditions, and that demonstrate the potential to address unmet medical needs for such diseases or conditions. The program is designed to facilitate development and expedite review of drugs to treat serious and life-threatening conditions so that an approved product can reach the market expeditiously.

RSV F Vaccine - Older Adults (60+ yrs)

Adults 60 years of age and older are at increased risk for RSV disease due to immunosenescence, the age-related decline in the human immune system. In this population, RSV is an important respiratory virus, distinct from influenza, that is frequently responsible for serious lower respiratory tract disease and may lead to hospitalization or even death. Additionally, RSV infection can lead to exacerbation of underlying co-morbidities such as chronic obstructive pulmonary disease, asthma and congestive heart failure. In the U.S., the incidence rate is approximately 2.5 million infections per year, and RSV is increasingly recognized as a significant cause of morbidity and mortality in the population of 64 million older adults. [3],[4] Based on our analysis of published literature applied to 2014 population estimates, the disease causes 207,000 hospitalizations and 16,000 deaths among adults older than 65. Annually, we estimate that there are approximately 900,000 medical interventions directly caused by RSV disease across all populations.

In July 2017, we announced positive top-line data from the Phase 2 clinical trial of our RSV F Vaccine in older adults known as E-205. The objective of the E-205 trial was to assess safety and immunogenicity to one and two dose regimens of the RSV F Vaccine, with and without aluminum phosphate or our proprietary Matrix-M adjuvant, in older adults. The trial was a randomized, observer-blinded, placebo-controlled trial which enrolled 300 older adults in the Southern Hemisphere. Participants were enrolled and vaccinated outside of the RSV season to best assess immunogenicity. Immunogenicity results indicate both aluminum phosphate and Matrix-M adjuvants significantly increased the magnitude, duration and quality of the immune response relative to RSV F antigen alone. All formulations and regimens were safe and well-tolerated. The data support the inclusion of adjuvanted formulations of our RSV F Vaccine in future older adult trials; those specific trial designs are currently being assessed.

Following the September 2016 announcement of the top-line results of Resolve™, our Phase 3 clinical trial of our RSV F Vaccine in older adults conducted during the 2015-16 RSV season in the U.S., we have conducted multiple analyses on the clinical data from the Resolve trial, the two other completed Phase 2 clinical trials conducted in older adults, and top-line data from the most recent Phase 2 trial conducted in 2017. Our analyses of these clinical trials sought to better understand their results. More detailed descriptions of each of these RSV older adult clinical trials are found in this “Clinical Trial Updates and Analyses” below; the trials are named and briefly described in the following table:



We have found that seasonal variation in attack rate may have a large impact on demonstrating vaccine efficacy in a particular year. In our E-201 trial, we witnessed a high attack rate and showed a clear demonstration of efficacy. In our Resolve trial the following year, we observed a primary endpoint attack rate of only one-fourth that of the previous season. This scenario is a conundrum that influenza vaccine developers have experienced for decades: “low attack rate” influenza seasons make it very difficult to demonstrate vaccine efficacy.

Additional further analyses of the Resolve trial data indicate that our RSV F Vaccine was associated with a 61% reduction in hospitalizations due to chronic obstructive pulmonary disease (“COPD”) exacerbations, and the same analysis of the E-201 trial showed a similar signal, supporting this finding. COPD exacerbations represent an unmet medical need and a significant healthcare cost burden. We plan to initiate a Phase 2 efficacy trial in older adults in 2018 that will evaluate COPD exacerbations as a prospective endpoint. We believe such a clinical pathway could lead to a pivotal study in a more susceptible, higher-risk population that could demonstrate vaccine efficacy using an endpoint that is less subject to seasonal variation of RSV disease.

In August 2015, we announced positive top-line data from a Phase 2 clinical trial of our RSV F Vaccine in 1,600 older adults. The clinical trial was designed to prospectively examine the incidence of all symptomatic respiratory illnesses associated with RSV infection, in community-living older adults who were treated with placebo. The trial also evaluated safety and immunogenicity of our RSV F Vaccine compared to placebo. Finally, the trial estimated the efficacy of our RSV F Vaccine in reducing the incidence of respiratory illness due to RSV. The trial was the first to demonstrate efficacy of an active RSV immunization in any clinical trial population. In the per protocol population, the clinical trial showed statistically significant vaccine efficacy in prevention of all symptomatic RSV disease (41%) and, in an ad hoc analysis, showed a decrease in RSV disease with symptoms of lower respiratory tract infection (45%) in older adults. The clinical trial established an attack rate for symptomatic RSV disease of 4.9% in older adults, 95% of which included lower respiratory track symptoms. Efficacy against more severe RSV illness, defined by the presence of multiple lower respiratory tract symptoms associated with difficulty breathing, was 64% in ad hoc analyses.

RSV F Vaccine - Pediatrics (6 mos – 5 yrs)

There are currently approximately 18 million children in the U.S. between six months and five years of age. [10] In the U.S., RSV is responsible for approximately 57,000 hospitalizations of children under five years of age annually, the vast majority of which occur in infants less than one year old, and especially those under six months of age.[11],[12],[13],[14],[15]

In September 2015, we announced positive top-line data from a Phase 1 clinical trial of our RSV F Vaccine in healthy children between two and six years of age. This clinical trial evaluated the safety and immunogenicity of our RSV F Vaccine, with one or two doses, with or without aluminum phosphate adjuvant. Trial enrollment was concluded with a smaller than planned cohort so that dosing could be completed ahead of the 2014-15 RSV season. The vaccine was well-tolerated and serum samples collected from a subset of 18 immunized children in the per-protocol population demonstrated that the RSV F Vaccine was highly immunogenic at all formulations and regimens. 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. We are assessing the next steps in the development of our RSV F Vaccine for pediatrics.


NanoFlu – Nanoparticle Seasonal Influenza Vaccine - Older Adults (65+ yrs)

Influenza is a world-wide infectious disease that causes illness in humans with symptoms ranging from mild to life-threatening or even death. Serious illness occurs not only in susceptible populations such as pediatrics and older adults, but also in the general population but also in the general population largely because of unique strains of influenza for which most humans have not developed protective antibodies. Current estimates for seasonal influenza vaccine growth in the top seven markets (U.S., Japan, France, Germany, Italy, Spain and UK), show a potential increase from approximately $3.2 billion in the 2012-13 season to $5.3 billion by the 2021-2022 season.

The Advisory Committee for Immunization Practices of the Center for Disease Control and Prevention (CDC) recommends that all persons aged six months and older be vaccinated annually against seasonal influenza. Influenza is a major burden on public health worldwide: an estimated one million deaths each year are attributed to influenza.17 It is further estimated that, each year, influenza attacks between 5% and 10% of adults and 20% to 30% of children, causing significant levels of illness, hospitalization and death.18 Recombinant seasonal influenza vaccines, like the candidate we are developing, have an important advantage: once licensed for commercial sale, large quantities of vaccines can potentially be manufactured quickly and in a cost-effective manner, without the use of either the live influenza virus or eggs.

After many years of developing seasonal influenza vaccine candidates as VLPs, we have identified advantages of developing a nanoparticle-based seasonal influenza vaccine. In particular, influenza nanoparticles can display conserved antigenic regions, which have the potential to elicit broadly neutralizing antibodies that may offer protection against a range of drifted strains. Additionally, nanoparticles offer improved purity and manufacturability and advantages for co-formulation with other nanoparticle-based vaccines.

In September 2017, we initiated a Phase 1/2 clinical trial of our nanoparticle seasonal influenza vaccine candidate including our proprietary Matrix-M adjuvant (“NanoFlu™”) in older adults. The trial is a randomized, observer-blinded, active comparator-controlled trial in approximately 330 healthy older adults. The primary objective of the trial is to assess the safety and immunogenicity of two concentrations (15 µg or 60 µg) of NanoFlu compared to a licensed influenza vaccine, Fluzone® High-Dose (“Fluzone HD”). Data from the trial are expected by February 2018.

Preclinical data in which NanoFlu was compared in a head-to-head challenge study against Sanofi’s Fluzone HD, currently the leading licensed influenza vaccine for the older adult market, as well as Sanofi’s regular dose seasonal influenza vaccine, was announced in August 2017 and provide a strong rationale for the initiation of the Phase 1/2 trial. Our NanoFlu vaccine demonstrated significantly stronger and broader immune responses against homologous and heterologous influenza strains, including a series of “drift” strains evolved across over more than a decade of influenza seasons. In a preclinical challenge study, we showed that our NanoFlu was protective against both a homologous virus and a ten-year old drifted strain. In parallel, we announced the achievement of significant improvements in manufacturing yields and product purity.


Combination Influenza / RSV F Vaccine - Older Adults (60+ yrs)

Given the ongoing development of our RSV F Vaccine and our nanoparticle-based seasonal influenza vaccines, we continue to believe in the long-term opportunity to develop a combination RSV/influenza respiratory vaccine. Early preclinical development efforts give us confidence that such a combination vaccine is feasible.

Ebola GP Vaccine

Ebola virus (EBOV), formerly known as Ebola hemorrhagic fever, is a severe, often fatal illness in humans. Multiple strains of EBOV have been identified, the most recent of which, the Makona strain, is associated with a case fatality rate of between 50% and 90%. There are currently no licensed treatments proven to neutralize the virus but a range of blood, immunological and drug therapies are under development. Despite the development of such therapies, current vaccine approaches target either a previous strain of the virus or were initially developed to be delivered by genetic vectors. In contrast, our EBOV glycoprotein vaccine candidate (Ebola GP Vaccine) was developed using the Makona EBOV strain.  

In July 2015, we announced data from our Phase 1 clinical trial of our Ebola GP Vaccine in ascending doses, with and without our Matrix-M adjuvant, in 230 healthy adults. Participants received either one or two intramuscular injections with or without adjuvant, or placebo, and immunogenicity was assessed at multiple time points, including days 28 and 35. These Phase 1 data demonstrated that our Ebola GP Vaccine is highly immunogenic, well-tolerated and, in conjunction with our proprietary Matrix-M adjuvant, resulted in significant antigen dose-sparing. Although the adjuvanted Ebola GP Vaccine was highly immunogenic at all dose levels, the adjuvanted two-dose regimens induced Ebola anti-GP antibody geometric mean responses between 45,000 and 70,000 ELISA units, representing a 500 to 750-fold rise over baseline at day 35. In 2015, we also announced successful data from two separate non-human primate challenge studies of our Ebola GP Vaccine in which, in both cases, the challenge was lethal for the control animal, whereas 100% of the immunized animals were protected.

1 Nair, H. et al., (2010) Lancet. 375:1545 - 1555
2 WHO Acute Respiratory Infections September 2009 Update:
3 Falsey, A.R. et al. (2005) NEJM. 352:1749–59 extrapolated to 2015 census population
4 Falsey, A.R. et al. (1995) JID.172 :389-94
5 Nair, H., et al., (2010) Lancet. 375:1545 - 1555
6 Hall, C.B. et al. (2013) Pediatrics; 132(2):E341-348
7 Oxford Vaccine Group:
8 Glezen, W.P. et al. (1986) Am J Dis Child; 140:543-546
9 Glenn, G.M. et al. (2016) JID; 213(3):411-12
10 U.S. Census. www.census.go/population/international/data/idb/informationGateway.php
11 Stockman, L.J. et al. (2012) Pediatr Infect Dis J. 31:5-9
12 CDC update May 5, 2015.
13 Boyce, T.G. et al. (2000) J Pediatr. 137:865-870
14 Hall, C.B. et al. (2009) NEJM. 360(6):588-98
15 Hall, C.B. et al. (2013) Pediatrics. 132(2):E341-8