Novavax Inc., a biotechnology company focused on the development and commercialization of next-generation vaccines against serious infectious diseases, today announced preliminary data evaluating the immune response of its vaccine COVID -19, NVX-CoV2373, against the Omicron variant, as well as additional data from the ongoing Phase 2 Boost study. The new results show broad cross-reactivity against the Omicron variant and other circulating variants after a primary 2-dose regimen, with responses increasing after the third dose at six months.
Immune responses included the following:
- Anti-spike IgG titers after dose 3 increased 5.4-fold (Prototype) to 9.3-fold (Omicron) over peak values observed after primary vaccination with 2 doses.
- This represents a 61.1-fold (prototype) and 73.5-fold (Omicron) increase over pre-dose 3 boost.
- Titers of ACE2 inhibition increased 6-fold (Prototype) to 19.9-fold (Omicron) compared with peak values after the 2-dose primary series. This corresponds to a 54.4-fold (Prototype), a 24.4-fold (Delta), and a 36.3-fold (Omicron) increase before the booster.
- Wild-type neutralization reactions were observed in prototype, delta, and omicron after 2 doses. Significant increases were observed after boosting, with titers for Delta and Omicron comparable to those associated with protection in phase 3 trials in the US, Mexico, and the UK.
- After 2 doses, neutralization of the Omicron wild-type < was 4-fold lower than the prototype, suggesting that both a booster dose and an Omicron-specific vaccine may be beneficial.
Further, data from the pediatric expansion of Novavax’ PREVENT-19 Phase 3 trial in the U.S. and Mexico showed robust immune responses in adolescents, including increased IgG and receptor inhibition titers against a wide array of variants, including Omicron, following a 2-dose series. Responses in adolescents were 2- to 4-fold higher than adults against all evaluated variants.
“In the midst of an evolving pandemic, NVX-CoV2373 showed strong immune responses against Omicron and other circulating variants. We are encouraged that boosted responses against all variants were comparable to those associated with high vaccine efficacy in our Phase 3 clinical trials, suggesting that NVX-CoV2373 can play an important role in the ongoing fight against new variants,” commented Gregory M. Glenn, President of Research and Development, Novavax. “Given the continued evolution of the coronavirus, the development of an Omicron vaccine could be necessary. Novavax has cloned, expressed and characterized the Omicron spike protein vaccine and will soon enter the GMP-phase of production. We expect to begin clinical studies in the first quarter of 2022.”
In an ongoing study, healthy adult participants were administered a single booster dose of 5 µg SARS-CoV-2 rS with 50 µg Matrix-M™ adjuvant approximately six months after their primary 2-dose vaccination series. Twenty-eight days after the booster dose, the immune response to SARS-CoV-2 was assessed with multiple tests.
Safety reports of reactogenicity events showed an increasing trend across all 3 doses of NVX-CoV2373, reflecting increased immunogenicity at a third dose. After booster vaccination, local and systemic reactions were generally short-lived, lasting a median of approximately 2 days. The incidence of grade 3 or higher events remained relatively low. Medically associated adverse events (MAAEs), potentially immune-mediated diseases (PIMMCs), and serious adverse events (SAEs) occurred infrequently after the booster dose and were balanced between the vaccine and placebo groups.
The main findings reported in ‘Immunogenicity and Safety Following a Homologous Booster Dose of a SARS-CoV-2 recombinant spike protein vaccine (NVX-CoV2373): A Phase 2 Randomized Placebo-Controlled Trial’ will be submitted for peer-reviewed publication and are expected to be available online at https://www.medrxiv.org/ in the next few days.
