BNT162a1

BNT162a1 is a uridine-modified messenger RNA (uRNA) vaccine candidate developed by BioNTech in collaboration with Pfizer for the prevention of COVID-19. It was one of four candidates (alongside BNT162b1, BNT162b2, and BNT162c2) evaluated in early-phase clinical trials to determine the optimal platform for a SARS-CoV-2 vaccine. BNT162a1 encodes the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Unlike the nucleoside-modified mRNA used in the eventually authorized Comirnaty (BNT162b2), BNT162a1 utilizes unmodified uridine, which typically induces a stronger innate immune response. Development of BNT162a1 was discontinued after Phase 1/2 trials in favor of the modRNA candidates.