As you're well aware by now, Trump is largely unconcerned with grifting. This is a guy that readily admits he could kill somebody and get away with it. IOW, he thinks his fans are that stupid, and so far he has been correct.
On the vaccine, I'm sure he will at some point. The problem is that he's been swinging and missing so much on covid, he lacks credibility on the subject right now. And he's going to have to work on that. Is he still doing the pressers he said he was going to restart last week or so?
There's one thing that has become clear, IMO, he can't change the narrative to something he feels more comfortable about, because covid has been relentless and unapologetic, and nothing catches more attention than dead americans.
And so I think he's realized he's just going to have go to in there and change the perception that he's a loser on covid. There's 3 more months to go, and there's going to be debates (I think?) and Joe Biden is on the other side, so he still has a chance to do that.