No. Pfizer indicated it could develop and begin mass-producing a variant-specific booster within 100 days, if a third dose of the original vaccine is ineffective. [0] But the plan is to use the existing stock.

I'd feel a lot safer if Pfizer started developing a polyvalent booster with mRNA for all significant variants.

0. http://ctmirror.org/2021/08/13/pfizer-ceo-to-public-just-tru...