Safety and Immunogenicity of SARS-CoV-2 Spike Receptor-Binding Domain and N-Terminal Domain mRNA Vaccine
Spyros Chalkias, Antionette Pragalos, Adebayo Akinsola, Gary Berman, Madhavi Ampajwala, Jay Meyer, Lorraine Schoch, Wen Zhou, Yamuna Devi Paila, Weiping Deng, Jing Feng, Elizabeth de Windt, Darin K. Edwards, Jacqueline M. Miller, Rituparna Das
Abstract
BACKGROUND: mRNA-1283 is an investigational coronavirus disease 2019 (COVID-19) mRNA vaccine encoding the receptor-binding and N-terminal domains of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein in contrast to the original mRNA-1273 vaccine, which encodes the full-length spike protein. METHODS: A phase 2a, dose-ranging, observer-blind, randomized study conducted in adults (aged ≥18 years) previously vaccinated with mRNA-1273 evaluated the safety and immunogenicity of a single dose of mRNA-1283 (2.5, 5, and 10 µg) and its bivalent formulation, mRNA-1283.211 (5 and 10 µg; encoding original SARS-CoV-2 and Beta) against the comparator mRNA-1273 vaccine, 50 µg (part A). A subsequent, open-label study (part B) evaluated the safety and immunogenicity of a monovalent Omicron BA.1 vaccine, mRNA-1283.529 (5 and 10 µg). RESULTS: A total of 340 participants were randomized in part A, and 200 participants were enrolled in part B. All dose levels of mRNA-1283 vaccines were well tolerated and increased the neutralizing antibody (nAb) responses at day 29 compared to baseline against SARS-CoV-2 D614G and Beta. The nAb responses elicited by mRNA-1283 were higher than those elicited by mRNA-1273. mRNA-1283.529 (part B) increased nAb at day 29 against Omicron BA.1. Antibody responses remained detectable for a year postvaccination. CONCLUSIONS: mRNA-1283 was well tolerated and exhibited improved immunogenicity compared to mRNA-1273. CLINICAL TRIALS REGISTRATION: NCT05137236.