Covid medical expenses have been covered by the cares act but that wont last forever. Insurance companies are trying to limit Covid coverage which may push a bunch of people into medical bankruptcy. A serious covid hospitalization if you survive is a very expensive ordeal.
Even if debtors prisons still existed, you likely would not be in good enough shape to work the debt off post C19. You'd probably be written off.
The issue of reeally understanding breakthrough infections would likely hinge on an accurate tally of originals vs subsequent varients by intervening time period between infection/reinfection....