BNT162b1 + BNT162b2

**BNT162b1 + BNT162b2** is a combination of two experimental nucleoside-modified mRNA (modRNA) vaccine candidates developed by BioNTech and Pfizer as part of the BNT162 program for COVID-19 prevention. **BNT162b1** encodes a trimerized receptor-binding domain (RBD) of the SARS-CoV-2 spike protein, while **BNT162b2** encodes the full-length prefusion-stabilized spike protein; both are formulated in lipid nanoparticles to induce neutralizing antibodies and T-cell responses against SARS-CoV-2. Evaluated in parallel Phase 1/2 trials, this pairing represents early candidates in the program, with BNT162b2 advancing to approval as Comirnaty due to superior tolerability, though the specific combination was explored for potential co-administration or comparative immunogenicity.