Pfizer Inc. and German partner BioNTech SE said Friday they have received fast track designation from the U.S. Food and Drug Administration for a single-dose-mRNA-based vaccine candidate targeting both COVID and flu. The companies already announced that they are in early-stage trials to review the safety and immunogenicity of their combined vaccine among healthy adults. The vaccine will target the BA.4 and BA.5 omicron sublineages, which have become dominant globally, as well as four different f