Data in from adults and adolescents aged 12-17 collected in a phase 3 trial of a prototype Novavax COVID-19 vaccine showed it had achieved its pre-specified immunologic endpoint.
Study 307 met its primary endpoint, showing three lots of the vaccine tested as a heterologous booster induced consistent immune responses in previously vaccinated adults aged 18-49.
Consistent safety profile
Gregory Glenn, president of research and development at Novavax, said: “These data further demonstrate the consistent immunogenicity and safety profile of the Novavax COVID-19 vaccine as a booster, regardless of previous vaccine history.
“They are an early indication that our vaccine may be effective against variants such as Omicron. We have ongoing trials further exploring the Novavax COVID-19 vaccine’s potential as an effective booster against these variants, including BA.4/5, and look forward to sharing these data.”
In the PREVENT-19 trial, a single homologous booster dose was given to select adult participants aged 18 and older, approximately eight or 11 months after their primary series. Following a booster dose, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) anti-spike (anti-S) Immunoglobulin G (IgG; a type of antibody) levels increased significantly relative to pre-boost levels, rising above the level correlated with 95% vaccine efficacy in a recent USG study.
Neutralizing antibodies against the prototype strain also increased by 34- to 27-fold compared to pre-boost levels when boosted at eight or 11 months. Boosting also increased IgG and human angiotensin converting enzyme 2 (hACE2) receptor inhibition antibody levels against Omicron BA.1, BA.2, and BA.5 variants, with levels that are comparable to those observed in phase 3 efficacy studies.
In the pediatric expansion of PREVENT-19 which evaluated boosting in adolescents, a single homologous booster dose was evaluated for anti-S IgG, hACE2 receptor inhibition and neutralization antibody responses. Following boosting, neutralizing titers were 2.7-fold higher than those seen with primary vaccination, and a significant boost was observed for antibody against Omicron BA.1, BA.2, and BA.5.
In both adults and adolescents, a third dose of the Novavax COVID-19 vaccine decreased the antigenic distance between SARS-CoV-2 variant and prototype virus strains, suggesting benefit for the prevention of COVID-19 against contemporary variants such as Omicron. Additionally, in both adults and adolescents, booster doses were well tolerated, with mostly mild to moderate reactogenicity that was of short duration.
Study 307 achieved its primary endpoint, showing that three lots of the Novavax COVID-19 vaccine induced consistent immune responses in adults aged 18- 49.
Further, heterologous boosting responses were consistent across participants who received primary vaccines from Moderna, Pfizer, or Johnson & Johnson, with IgG levels approximating levels observed in PREVENT-19.
The Novavax COVID-19 vaccine (NVX-CoV2373) is a protein-based vaccine engineered from the genetic sequence of the first strain of SARS-CoV-2, the virus that causes COVID-19 disease. It is packaged as a ready-to-use liquid formulation in a vial containing ten doses.
The vaccination regimen calls for two 0.5 ml doses given intramuscularly 21 days apart.