The number of clinical trials to find a vaccine or therapy for Covid-19 continues to rise, with over 2,581 currently planned, ongoing or completed. One of the leading vaccine candidates is mRNA-1273 by Moderna. The drug is a messenger ribonucleic acid (mRNA)-based vaccine designed to express the coronavirus spike protein based on the genomic sequence of 2019-nCoV. It is administered through the intramuscular route as a lipid nanoparticle. The drug candidate received Investigational New Drug (IND) application approval from the FDA on 6 May 2020 to initiate a Phase II trial and received Fast Track Designation on 12 May 2020.

On 14 July 2020, Moderna announced the publication of interim results in The New England Journal of Medicine from its Phase I clinical trial of mRNA-1273. The study, which was led by the National Institute of Allergy and Infectious Diseases, was initiated in March 2020 and enrolled 120 adult subjects (at least 18 years of age). Subjects were split into 13 different cohorts, segmented by age (18–55 years, 56–70 years, and 71 years and older) and dosage (25μg, 100μg, and 250μg), and received a two-dose vaccination schedule that was 28 days apart. The recently published preliminary results were based on 45 adult patients, ages 18–55 years, who were enrolled at either Kaiser Permanente in Seattle, Washington, US or Emory University in Atlanta, Georgia, US. The results demonstrated no serious adverse events, only minor side effects, and noted the drug was well tolerated while inducing binding antibodies to the SARS-CoV-2 spike protein in all patients.

With these promising results, Moderna is looking to initiate a Phase III clinical trial in late July 2020 using the drug candidate in a much larger patient pool. Moderna plans to enrol 30,000 patients at 87 locations across the US. The randomised, placebo-controlled trial will consist of two groups; one will receive 100μg of mRNA-1273 and the other will receive a placebo. The aim of the trial will be to establish whether the primary endpoints of prevention of symptomatic Covid-19 disease are achieved in the vaccine-treated group.

With the Phase II trial currently ongoing and the Phase III trial to begin shortly, more results will provide additional evidence and a better assessment of mRNA-1273 as an effective vaccine for Covid-19. If successful, this will be the first mRNA vaccine to seek marketing authorisation.