Speculation. We're rightly worried about a pandemic, but with lower vaccination, existing respiratory viruses, and some nasty strains, all hammering our immune systems, a "Multidemic" is probably a legitimate worry.

Get COVID and your weakened immune system means you get walking pneumonia. Get rsv and you're vulnerable to the flu. Unvaxxed kids spreading measles and when they recover they get COVID.

It'd be harder to fight due to shifting infection rates and chains.