Wow, look what I missed today!
I can only beg to ask what was Joe Biden talking about last week when he mentioned "Novavax."
Anyway, from this earlier post we have worked with 3M-052-SE adjuvant. It has emerged as one of the best for our antigens.
I'm surprised that 15 ug of the soluble version of the spike protein did so well so yes,
it's the adjuvant.
This soluble version is missing the heptad repeat, transmembrane domain and cytoplasmic tail.
Using the secreted protein expression methodology seen here we know expression levels are pretty low in these cells.