The early-stage study will assess the safety and immunogenicity of mRNA-1283 at three dose levels, and will be given to healthy adults either as a single dose or in two doses 28 days apart, the company said.
Last week, Moderna began dosing the first participants in a study testing its COVID-19 booster vaccine candidates.
The COVID-19 shot is the fourth to be endorsed for use in the EU after vaccines from Pfizer-BioNTech , AstraZeneca-Oxford University and Moderna, and is recommended for those over 18 years of age.
With this latest positive opinion, authorities across the European Union will have another option to combat the pandemic and protect the lives and health of their citizens.
Overall, among 39,321 participants across all regions, the efficacy against severe Covid-19 was 85.4 percent, but it fell to 66.1 percent when including moderate forms of the disease.
A study released on Wednesday, showed reduced neutralization of the South Africa-like virus by blood from people who had been immunized with the Pfizer-BioNTech vaccine.