(2) The evaluation is part of the Phase 1/2/3 trial and will study a third dose of the Pfizer-BioNTech COVID-19 vaccine, BNT162b2, at 30 µg that will be given to Phase 1 participants to evaluate the safety and tolerability of a booster vaccine Discussions with regulatory authorities are ongoing regarding an additional registration-enabling study using an mRNA vaccine with a variant sequence; this would provide a flexible solution for rapidly adapting the vaccine for use against the B.1.351 lineage or other new strains that may emerge as possible immune escape virus variants Based on in-vitro studies conducted to date and observations from real world evidence, the Companies have not observed changes to neutralizing antibody levels that would predict a significant reduction in protection provided by two doses of BNT162b2