This seems to be unverified and Truth Social AI says,

"Short answer: No clear evidence shows Donald Trump himself called vaccines “poison.” He has repeatedly praised several vaccines (including COVID-19) as “amazing” and said “vaccines that work…should be used.”[1]

Essential context:

In 2024 remarks about Florida moving to eliminate vaccine mandates, Trump said “some vaccines…are so amazing,” citing polio and the COVID-19 vaccines developed under Operation Warp Speed, and added “there are vaccines that work…they just pure and simple work.”[1]
The “poison” phrasing appears in related coverage of others: Florida Surgeon General Joseph Ladapo has taken hard-line positions against mandates, and Fox News’ piece notes the COVID-19 vaccine was referred to as “poison” in that context, but does not attribute that word to Trump.[1][5]
If you’re referencing recent policy shifts: Reporting says the Trump administration plans to end routine federal guidance recommending COVID vaccination for kids and pregnant women, a move that departs from his first-term promotion of the shots; but this policy change is not the same as calling vaccines “poison.”[2]
https://bioclandestine.substack.com/p/trump-calls-vaccines-poison