>Yes, I'm interested to see latest efficiency figures for the J&J or Novavax. FWIW, Novavax uses the same traditional underlying technique as some older vaccines (e.g. Hepatitis) so may start less efficacious but end up more effective as the beastie mutates.

https://www.nature.com/articles/d41586-021-02261-8
The results raise questions about whether it could be more effective to have doses of different vaccines, rather than multiple doses of the same one, especially if a third, booster dose is to be considered. Georg Behrens, an immunologist at Hanover Medical School in Germany, says that mixing vaccines could increase their effectiveness. The immune system reacts differently to different types of vaccine — and this could be exploited to trigger a better overall response. “Using a vector-based one first and then something that has no vector, but the same antigen, absolutely makes sense,” says Behrens.

Seems my June logic gets more supporters - although current "only mRNA" comparison favors Moderna over Pfizer on holding effectiveness high against delta.