Why covid-19 might finally usher in the era of health care based on a patient's data

Infectious diseases don't get much more personalized than covid-19. No one can explain with any certainty why seemingly similar individuals respond so differently to exactly the same pathogen. Why do some of us get a case of the sniffles, and others end up on a ventilator? Why are so-called long-haulers left with lingering problems, yet other people recover fully? Why do some never show symptoms at all?