Uh, no. Biden has not let antivaxxer morons be morons, he actively worked against that through public messaging advocating vaccinations and through increasing vax availability.
What DID Trump do? And what's the opposite of 'let'? Mandates?
The Covid cases and deaths in '21 are the legacy of Trump's dumb-ass politicization of his Covid response. The states hardest hit contain most of his supporters.