Novavax COVID-19 vaccine data supports homologous and heterologous boosting

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.”

Booster dose

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.

COVID-19

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.

Protein-based vaccine

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.

Intramuscular dose

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.