There are lots of papers which look at antibodies — because antibodies (made by B cells) are comparatively easy to measure. Over and over, I’ve seen papers saying that some specific vax does not generate as many antibodies against some specific variant than against COVID Classic.
By contrast, this paper looks at T-cells in the blood of people vaccinated by mRNA vaxes, and says that the T-cells were pretty much equally effective against COVID Classic, B.1.1.7, and B.1.351, and that a second dose makes more T-cells but not better (more specific) ones. The study also found that if you had been infected with COVID, a second dose didn’t do much good. Go T-cells!
A Canadian company, Providence Therapeutics, says it has gotten promising results from the Phase 1 trial of its mRNA vaccine.