If you believe Tony Jay on Balloon-Juice, Corbyn was being undercut by Blarites (and the press) and others who would rather destroy the Labour party than see him win. Dunno. But regardless, tens of thousands have died under BoJo that probably wouldn't have died under Labour.

Heh, that's the opposite of what actually happened. Corbyn's enablers (a pressure group called Momentum, plus the purity ponies in the Party membership at large, whose jobs didn't depend on an effective leader) kept him there despite there being literally years of evidence that he was shit at every single aspect of being Leader of Her Majesty's Opposition. Party before country, writ large.

And I don't have any confidence that a Corbyn government would have had a long-term better outcome. I think they'd have locked up so hard that the economy tanked completely, and whilst there would be short-term wins in terms of COVID-19 deaths, millions more would have shitty, shorter lives, because poverty is a motherfucker.