I can't speak for him, and obviously tweets are short enough they can't contain it either. But apparently the plan was (a) to use federal funds and manpower to get vaccines spread as widely as possible. There was an early goals of 100M doses in the first 100 days, which was met, and another goal was set and met [1]. Another factor was sending the message: this isn't a "Democrat hoax", that it is real, is killing people, the vaccines are safe and certainly much safer than getting covid. I say that has been accomplished.

On the other hand, there is a large contingent of people and talking heads who have tried their hardest to spread fear and misinformation. We are still at something like 60% inoculated, and many doses of the vaccine ended up going bad or were shipped overseas because not enough people trust the vaccine.

Third, there is no way to prevent novel variants from causing new problems, other than getting the old variants under control to reduce the vast pool of variant breeders.

[1] https://www.bbc.com/news/56901183

[EDIT] Also, your terse "he claimed there was a federal solution" is also subject to debate. He said he had a plan, but that doesn't mean the plan was a federal-only solution.