Despite an uptick in vaccine skepticism among Americans, Pennsylvania doctors lauded the Food and Drug Administration’s approval Wednesday of the first mRNA flu vaccine. Moderna also produces an mRNA vaccine for respiratory syncytial virus, or RSV. The benefit of mRNA vaccines, however, is how rapidly they can be deployed. Ultimately, he said the approval of the mRNA vaccine could cut the roughly six-month lead times for traditional flu vaccines in half. But it remains an open question whether mRNA vaccines ultimately could displace traditional flu jabs, Hotez said.