Study design
This is an open-label, ongoing, phase 2/3 study to evaluate the immunogenicity, safety and reactogenicity of various modified mRNA-1273 vaccine candidates against COVID-19 administered as boosters (mRNA-1273.211 (Part A.1), mRNA-1273 (Part B), mRNA-1273.617.2 (Part C), mRNA-1273.213 (Parts D and E), mRNA-1273.529 (Part F), mRNA-123.214 (Part G and Part A.2) and mRNA-1273.222 (Part H) vaccines; clintrials.gov NCT04927065). Part H interim results are reported here. Part H evaluates the safety, reactogenicity and immunogenicity of the bivalent Omicron BA.4/BA.5-containing mRNA-1273.222 (25 µg each of two mRNAs encoding the ancestral SARS-CoV-2 (Wuhan) and Omicron variant (BA.4/BA.5) spike sequences) booster vaccine compared to the currently authorized mRNA-1273 booster in adults who had previously received a two-injection primary series (100 µg) and first booster doses (50 µg) of mRNA-1273 in the COVE trialParticipants were enrolled in a sequential, nonrandomized manner and received single-second boosters of the within-study noncontemporaneous 50 µg mRNA-1273 (enrolled between 18 February and 8 March 2022) or 50 µg bivalent mRNA-1273.222 (enrolled between 10 August and 23 August 2022). Data are reported for the mRNA-1273 group (Part F, cohort 2) based on the data cutoff date of 6 July 2022 at the day 91 interim analysis