The vaccine was jointly developed by Moderna and the U.S. National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health (NIH) as part of the Accelerating COVID-19 Therapeutic Interventions and Vaccines (ACTIV) public-private partnership. Moderna is leading the trial and is providing its investigational vaccine. The Biomedical Advanced Research and Development Authority and the NIH are providing financial support for the trial as part of Operation Warp Speed.

The trial will also be a part of the NIH Coronavirus Prevention Network (COVPN). The vaccine candidate will be tested at approximately 89 clinical research sites in the U.S., 24 of which are part of COVPN.

The phase III blinded trial will evaluate the safety of mRNA-1273 and determine if the vaccine can prevent symptomatic COVID-19 after two doses. Volunteers will receive two intramuscular injections approximately 28 days apart. Participants will be randomly assigned to receive either two 100-microgram injections of mRNA-1273 or two shots of a saline placebo. Researchers will collect and analyze blood samples to detect and quantify immune responses to SARS-CoV-2.

The Data and Safety Monitoring Board, an independent committee, will review blinded and unblinded data at regular timepoints to assess the safety of the vaccine candidate.