For months, Joseph R. Biden Jr. has gone to great lengths to model responsible behavior in the coronavirus era. He wears masks in public. He does not hold crowded rallies. When he gives speeches, reporters sit at a distance from one another, with white circles on the ground to mark their turf.
These actions have so far helped keep Mr. Biden healthy and able to continue campaigning while President Trump, who mocked masks and held large events, is now hospitalized with Covid-19.
But beyond the public examples of safety precautions, Mr. Biden’s health protocols have remained largely under wraps, with