Novavax has announced initial data evaluating the immune response of its COVID-19 vaccine, NVX-CoV2373, against the Omicron variant as well as additional data from its ongoing Phase 2 booster study.
“New results demonstrate broad cross-reactivity against Omicron and other circulating variants from a primary 2-dose regimen, with responses that increased following a third dose at six months,” Novavax said in a news release.
Immune responses included the following:
- Anti-spike IgG titers after Dose 3 increased 5.4-fold (prototype) to 9.3-fold (Omicron) from peak responses seen after 2-dose primary vaccination. This represents a 61.1-fold (prototype) and a 73.5-fold (Omicron) increase from prior to the Dose 3 boost.
- ACE2-inhibition titers increased 6-fold (prototype) to 19.9-fold (Omicron) compared to peak responses following 2-dose primary series, representing a 54.4-fold (prototype), a 24.4-fold (Delta) and a 36.3-fold (Omicron) increase from prior to the booster.
- Wild-type neutralization responses were observed after 2 doses for prototype, Delta and Omicron. Significant increases were observed after boosting, with titers for Delta and Omicron comparable to levels associated with protection in U.S. and Mexico and U.K. Phase 3 studies.
- After 2 doses, Omicron wild-type neutralization was <4-fold lower than prototype, suggesting that both a booster dose as well as 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.
As part of an ongoing study, a single booster dose of 5 µg SARS-CoV-2 rS with 50 µg Matrix-M adjuvant was administered to healthy adult participants approximately six months after their primary 2-dose vaccination series. Multiple assays were used to evaluate immune responses against SARS-CoV-2 twenty-eight days following the booster dose.
