MRNA Vaccines Will Require 3 Doses From Start, Fauci Predicts

Future administration of mRNA vaccines like Pfizer-BioNTech SE and Moderna Inc.'s will likely require three doses from the start, instead of two doses plus a booster, Anthony S. Fauci said.

If implemented as the top infectious disease expert predicted, the third shot would become part of the primary series, potentially changing the vaccine label and plan for administering shots altogether.

“It should be a proper one from the get-go—three shots. And the reason we didn’t know that right away was because we were dealing with such an emergency situation that we needed to show the vaccine was effective and safe, ...