I don’t know why you’re being downvoted; for sure, one issue that I see skipped over is what we called “competence” — HIV is incompetent, whereas flu is compete

I don’t know why you’re being downvoted; for sure, one issue that I see skipped over is what we called “competence” — HIV is incompetent, whereas flu is competent: regardless of transmissivity (Re), you can ask how easily a virus infects. HIV rarely infects; flu infects quite well. It might be that COVID is supercompetent. That might explain the “breakthroughs” you’re reading about.