The main difference is that malaria, as bad as it is, is not contagious between people. So while the numbers are bad, there’s effectively a lid on them—they aren’t suddenly going to start growing exponentially.

With covid, the worst case scenario with no mitigation is quite literally that everyone in the world gets it in fairly short order, which could cause tens of millions of deaths even with low IFR estimates, plus all the social and economic destabilization that implies.