Pfizer (NYSE:PFE) and BioNTech (Nasdaq:BNTX) have begun a Phase 1 study to investigate the next-generation BNT162b4 COVID-19 vaccine candidate that could potentially result in a stronger and more durable immune response. Known as BNT162b4, the vaccine candidate has a T cell antigen mRNA encoding for SARS-CoV-2 non-spike proteins that are conserved across various variants. The…