From other articles it sounds like CDC and ACIP were given Biden admin priority and deemphasized the FDA role
I got that, Gruber at least, was pissed that the Biden administration said boosters were to start by a certain date. Implying that the FDA would approve and given a short deadline to do so.
However, Mr Splinty, I have been digging and I think Gruber and Krause are frustrated by much more than that. Hopefully we will get a tell all after they retire. Or a better researcher and journalist will get to the bottom of it, because I had 10 windows open and was speed reading.
I saved a few articles and will get into it deeper when I have more time. But it looks like in the vaccine committee meeting on June 10, 2021 there were some hard questions being asked and someone called on Gruber to answer. She pretty much shut it down and said those questions didn't need to be asked there (or maybe at that time) and would be discussed with the vaccine manufacturers. (I Need to go back to find out what the questions were)
Then interestingly, I found a paper published June 23, 2021 by Krause and many co-authors, one being Gruber about SARS-COV-2 variants and vaccines. Again, I only skimmed but it sounded like Krause is not happy with the way the studies and trials are being conducted, or rather he detailed how he thought they should be done. He also addresses some other issues about vaccines and variants.
With the standard disclaimer that it was not the views of his employers, of course.
Lol
Again, with my skimming, I got the impression that he thinks the vaccine should be modified to the new variants. He believes continuing to distribute the vaccine as it is now may be doing harm (he can't tell because the right data isn't being collected). May explain why he and Gruber were so frustrated about the booster being announced.