WASHINGTON, United States (AFP) — Pfizer and BioNTech on Monday submitted preliminary clinical data to US health authorities as part of their effort to seek authorization for a third dose of their Covid-19 vaccine for all Americans. Last week, the United States approved the booster shot of Pfizer-BioNTech and Moderna vaccines for people with weakened immune systems. Pfizer and BioNTech presented the results of their Phase One trial that evaluated the safety and efficacy of […]