Novavax Prototype COVID-19 Vaccine Data Support Homologous, Heterologous Boosting for Variants

Data from the phase 3 PREVENT-19 trial and Study 307 highlighted that adults aged 18 years and older and adolescents aged 12 through 17 years showed the prototype Novavax COVID-19 vaccine achieved its pre-specified immunologic endpoint, according to a Novavax press release.

The Novavax protein-based COVID-19 vaccine is engineered from the genetic sequence of the first strain of SARS-CoV-2. The vaccine uses Novavax’s recombinant nanoparticle technology to generate antigen derived from the COVID-19 spike protein and is formulated with Novavax’s patented saponin-based Matrix-M adjuvant to bolster the immune response and stimulate high levels of neutralizing antibodies.

The vaccine is in a ready-to-use liquid formulation in a vial containing 10 doses, with the vaccination regimen calling for a pair of 0.5 ml doses administered intramuscularly 21 days apart.

PREVENT-19 is a 2:1 randomized, placebo-controlled trial evaluating the efficacy, safety, and immunogenicity of NVX-CoV2373 with Matrix-M adjuvant in 29,960 participants 18 years of age and older in 119 locations in the United States and Mexico. The primary endpoint for PREVENT-19 was the first occurrence of PCR-confirmed symptomatic (mild, moderate, or severe) COVID-19 with onset at least 7 days after the second dose in serologically negative adult participants at baseline. The secondary endpoint was the prevention of PCR-confirmed, symptomatic moderate or severe COVID-19.

A single homologous booster dose was given to select adult participants 18 years of age and older approximately 8 or 11 months after their primary series in the PREVENT-19 trial. Following a booster dose, SARS-CoV-2 anti-spike (anti-S) immunoglobulin G (IgG) levels increased significantly relative to pre-boost levels, which rose above the level correlated with 95% vaccine efficacy in a recent study.

Neutralizing antibodies against the prototype strain also increased by 34- to 27-fold compared to pre-boost levels when boosted at 8 or 11 months. Additionally, boosting increased IgG and human angiotensin converting enzyme 2 (hACE2) receptor inhibition antibody levels against Omicron BA.1, BA.2, and BA.5 variants.

In the pediatric expansion of PREVENT-19, which analyzed boosting in adolescents between 12 and 17 years of age, a single homologous booster dose was evaluated for anti-S IgG, hACE2 receptor inhibition, and neutralization antibody responses.

In both adult and pediatric populations, a third dose of the Novavax COVID-19 vaccine decreased the antigenic distance between SARS-CoV-2 variant and prototype virus strains, which suggests benefit for the prevention of COVID-19 against contemporary variants, such as Omicron. Additionally, in both populations, booster doses were well tolerated, with mostly mild to moderate reactogenicity that was short of duration.

No new safety signal was observed through the placebo-controlled portion of the study. Among adolescent participants, solicited adverse events following administration of any dose included injection site pain or tenderness (75%), headache (56.9%), fatigue or malaise (57.9%), muscle pain (49%), nausea or vomiting (19.9%), joint pain (16.2%), fever (16.9%), injection site swelling (8%), and injection site redness (7.5%). Most were mild to moderate in severity and lasted less than 2 days.

REFERENCE

Novavax Prototype COVID-19 Vaccine Data Support Homologous and Heterologous Boosting and Suggest Benefit Against Variants. Novavax. October 12, 2022. Accessed October 14, 2022. https://ir.novavax.com/2022-10-12-Novavax-Prototype-COVID-19-Vaccine-Data-Support-Homologous-and-Heterologous-Boosting-and-Suggest-Benefit-Against-Variants