Part of the allure of mRNA vaccines is the ease with which they can be updated, but that capability has not yet been utilized to combat new variants of SARS-CoV-2, WBUR reports, noting that vaccine developers have been working on Delta-specific vaccines.
But, according to WBUR, a Delta-specific vaccine might not add that much more protection. The original vaccines, which are targeted at the viral spike protein, provide a high degree of protection against severe disease and hospitalization from the Delta variant. Dan Barouch, an immunologist at Beth Israel Deaconess Medical Center who worked on the Johnson & Johnson vaccine, tells it that Delta's spike protein isn't that different from that of the original strain. Instead, he tells it that Delta likely causes breakthrough infections through its high infectiousness and the sheer number of viral particles it produces.
At the same time, WBUR says that as there are currently vaccine doses going unused in the US and the introduction of a new, variant-specific vaccine might further undermine their adoption.
Instead, the Broad Institute's Bronwyn MacInnis tells it that the vaccines' reprogrammability might be best saved for any future variant with a more changed spike protein.