Parasites seem to reduce mortality associated with Covid, and Africa has a high parasite burden. More research is needed, but this is a reasonably sized study (751 patients):
It's a cool idea, but without specific examples, it's hard to evaluate the validity of it. And without them, it's guilty of doing exactly what it accuses others of doing: polluting the mindscape with ideas that most people find difficult to verify.
https://mead.uslakes.info/Level/