Adjuvanted Novavax Booster Adapts to New Variants

This past week, Novavax’s adjuvanted COVID-19 vaccine was authorized as the newest heterologous booster shot in the US.

The Novavax booster, NVX-CoV2373, was previously authorized in other geographies, including in the European Union. In the US, it will be the third COVID-19 booster dose, along with Pfizer-BioNTech and Moderna, available after a primary vaccine series.

At the IDWeek conference, we sat down with Novavax executive director, Clinical Development, Germán Áñez, MD, to learn more about this new non-mRNA booster vaccine.

At 1 month after receiving the Novavax booster vaccination, Añéz said, trial participants had both neutralizing antibody titers and binding IgG titers that were approximately 3 times higher than after primary vaccination. This fulfilled the noninferiority criteria.

Añéz said these results were largely expected, but a surprising result was how well the booster performed against Omicron subvariants. “We tested samples against 3 different flavors of the Omicron variant, BA.1, BA.2, and BA.5,” he said, emphasizing they found high titers even though the booster vaccine does not contain an Omicron sequence.

“Those titers were as high as the titers observed after the primary vaccination against Wuhan, and that is correlated with an efficacy of over 90%.” Añéz said these results remained consistent across variables such as time after vaccination and participant age.

NVX-CoV2373’s adjuvanted technology “is allowing the vaccine to perform as it is performing right now, meaning it has kept recognizing variants that arise,” Añéz explained.

“The adjuvant is responsible for these strong humoral responses that we have observed thus far against all variants that we have tested.”