(FILES) This file photo illustration picture shows vials with Covid-19 Vaccine stickers attached, with the logo of US pharmaceutical company Pfizer, on November 17, 2020. - Pfizer and BioNTech announced on July 8, 2021 they would seek regulatory authorization for a third dose of their Covid-19 vaccine. It comes after initial data from a trial showed a third shot pushed antibody levels five to 10 times higher against the original strain and the Beta variant compared to the first two doses alone, according to a statement (Photo by JUSTIN TALLIS / AFP)