Moderna has started dosing participants in the Phase III clinical trial of its Covid-19 vaccine candidate, mRNA-1273.

The study, named COVE, is being performed in alliance with the National Institute of Allergy and Infectious Diseases (NIAID) and the Biomedical Advanced Research and Development Authority (BARDA).

During the randomised, placebo-controlled trial, a 100µg dose of the vaccine candidate will be assessed in around 30,000 participants in the US.

The primary endpoint will be the prevention of symptomatic Covid-19, while key secondary endpoints include the prevention of severe Covid-19 and infection by SARS-CoV-2, irrespective of symptomology.

Moderna said that the primary efficacy analysis of the trial will be event-driven and depend on the number of participants with symptomatic Covid-19.

An independent Data and Safety Monitoring Board will review the study results.

Moderna CEO Stephane Bancel said: “We are pleased to have started the Phase III COVE study. We are grateful to the efforts of so many inside and outside the company to get us to this important milestone.

“We look forward to this trial demonstrating the potential of our vaccine to prevent Covid-19, so that we can defeat this pandemic.”

The company is working with contract research organisation PPD to conduct the COVE study. PPD supported the Phase II trial of the vaccine candidate, which completed the enrolment of 600 participants at eight sites within one month.

Moderna has chosen almost 100 sites with representative demography and is working with those sites to enrol volunteers at increased risk of Covid-19 infection.

An interim analysis of a Phase I trial assessing the Covid-19 vaccine candidate found the product to be generally safe and well-tolerated. The findings have been published in the New England Journal of Medicine.