Just notice the final lines from this article that comes from a left-wing news site:
"The former president and his wife Melania Trump did not appear in a public service announcement released on Thursday encouraging COVID-19 vaccinations and featuring all of the other living former U.S. presidents and their spouses."
I hope we find out why this is his stance. Its an incredibly Machiavellian move but may be necessary for the normies. I think he knows his bases opinion on vaccines as a whole.