https://news.yahoo.com/trump-dismisses-covid-19-booster-184022005.html
It sounds like Trump is now beginning to publicly cast some doubt on the vaccines. He's starting cautiously, by questioning the booster shots, but I suspect (hope) that he will be slowly ramping up the questioning and criticism going forward, from here on out.
He did earlier lambast mandates (he always said it should be a personal choice) and has been vocally against giving it to children. I'm had a feeling this would eventually come as well since for optics he had to continue to own Operation Warp Speed (which only got them out quicker) but then gradually sow doubts that Big Pharma and the Democrats were fucking it up after he had left.