A clinical trial involving 11,454 participants aged 12 and older across the U.S., U.K., and Canada evaluated two bivalent mRNA vaccines targeting SARS-CoV-2: mRNA-1283.222 and mRNA-1273.222. Conducted from March to August 2023, results showed mRNA-1283 demonstrated a relative vaccine efficacy (rVE) of 9.3% over mRNA-1273 and higher rates of neutralizing antibodies against the omicron variants. The study found comparable adverse event rates, mostly mild or moderate, with serious adverse events investigated for potential links to vaccination. The findings support mRNA-1283 as a promising COVID-19 booster option.

Source: The Lancet Infectious Diseases