As for COVID, would we have a vaccine yet if Clinton were president? Would we even be out of lockdowns?
Alt-History is uncertain by definition, but ...
The NIH probably would have started working with Moderna in January 2020, as happened in real life; ditto with AbCellera and its monoclonal antibody (mab) treatment development; these were relationships that existed at a level below the Presidential, probably (though HilLIARy was a bit of a micro-manager type);
Shutting down China travel would have been delayed 1-2 months, basically around the time China shut down travel;
The organizational infrastructure Trump got set up in January and February would have been delayed a month or two;
Testing of treatments and vaccines would not have been handled with urgency; Remdesivir and the mabs from AbCellera and Regeneron would probably have been authorized in early 2021, and approved in late 2021 or early 2022 (i.e. a 9-12 month delay); vaccine authorizations would probably have been delayed by a year or more, and unlike Trump's Operation Warp Speed, HilLIARy would have done little to organize/facilitate production of the vaccines, syringes, needles, fill/finish, or distribution to the states.
Unlike Trump, HilLIARy would have done little to organize/facilitate production and distribution of ventilators, PPE, and other materials necessary for hospitals.
Just off the top of my head.