What is the mRNA-1273 coronavirus disease 2019 (COVID-19) vaccine?

Updated: Feb 28, 2021
  • Author: David J Cennimo, MD, FAAP, FACP, AAHIVS; more...
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  • Genetic-code vaccine
  • Dose: 2 injections 28-days apart
  • No dilution required
  • Shipping and long-term storage: Frozen (-20°C) for 6 months
  • After thawing: Standard refrigerator temperatures (2-8°C) for 30 days
  • Room temperature: Up to 12 hours

The mRNA-1273 (Moderna Inc) vaccine encodes the S-2P antigen. The US phase 3 trial (COVE) launched on July 27, 2020. The trial was conducted in cooperation with the National Institute of Allergy and Infectious Diseases and included more than 30,000 participants who received two 100-mcg doses or matched placebo on days 1 and 29. Results showed an overall efficacy of 94.1% for the original viral strain. There were 196 confirmed cases (185 in placebo group and 11 in vaccine group). Among the 185 cases in the placebo group, 30 cases were severe, including 1 death. [10]   

The COVE study (n = 30,420) included Americans 65 years and older (24.8%), younger individuals with high-risk chronic diseases (16.7%), individuals who identify as Hispanic or Latinx (20.5%), and individuals who identify as Black or African American (10.4%). [10]  

Immunogenicity data at 90 days after the second vaccination was evaluated in 34 participants in the phase 3 trial. [11]  A phase 2/3 trial in adolescents 12-17 years begun in December 2020 is expected to enroll 3,000 participants.

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