The recent CDC study [1] suggests that vaccine efficacy against hospitalization for people 65+ is ~80% in the US. If we have reason to believe that a third vaccine dose would increase that efficacy, and the immunological data suggests that we do, then IMO it's clearly the right thing to do. Incontrovertible data will mean many seniors being hospitalized and dying in the interim.
There's so much we can do to increase the global supply of vaccines without sacrificing American citizens. Let's focus on those things to improve vaccine equity.
As long as the real rate of return is positive and wealthy people have a higher income or save a higher percentage of their income, inequality will increase. Hence inequality almost(?) always increases in times of stability. You don't need low interest rates to tell that story.
T bond yields are determined by auction, so the Fed does not have full discretion over long term interest rates. That's why the 30yr yield has fluctuated between 1.6-2.5% this year even though the overnight rate has not changed.