On Aug. 5, 2021, Novavax announced preliminary data demonstrating that a single booster dose of its recombinant nanoparticle protein-based COVID-19 vaccine with Matrix-Mﾙ adjuvant, NVX-CoV2373, given six months after an initial two-dose regimen, elicited a 4.6-fold increase in functional antibody titers.

Additionally, functional ACE-2 binding inhibition antibodies cross-reactive with the Delta (B.1.617.2) variant were more than 6-fold higher than the primary vaccination series. Complete data from the study will be submitted to a peer review publication and posted to a preprint server.