Dr. Lisa Jackson of Kaiser Permanente Washington Health Research Institute in Seattle and colleagues conducted a first-in-human Phase 1 clinical trial in healthy adults to evaluate the safety and immunogenicity of an investigational anti-SARS-CoV-2 vaccine called mRNA-1273. According to their report published in the New England Journal of Medicine, the vaccine candidate was generally well tolerated and prompted neutralizing antibody activity in all participants. The trial is supported by the NIH/National Institute of Allergy and Infectious Diseases (NIAID).
Fig: Colorized scanning electron micrograph of a cell (green) infected with SARS-CoV-2 virus particles (purple), isolated from a patient sample. Image credit: NIAID.
The mRNA-1273 vaccine candidate, manufactured by Moderna, Inc. of Cambridge, Massachusetts, is designed to induce neutralizing antibodies directed at a portion of SARS-CoV-2’s spike protein, which the virus uses to bind to and enter human cells.
In the preliminary report, Dr. Jackson and co-authors detailed the findings from the first 45 participants (18 to 55 years old) enrolled at the study sites in Seattle and at Emory University in Atlanta.
Three groups of 15 participants received two intramuscular injections in March and April 2020 of either 25, 100 or 250 micrograms (mcg) of the mRNA-1273 vaccine.
All the participants received one injection; 42 received both scheduled injections.
Regarding safety, no serious adverse events were reported.
More than half of the participants reported fatigue, headache, chills, myalgia or pain at the injection site.
Systemic adverse events were more common following the second vaccination and in those who received the highest vaccine dose.
Data on side effects and immune responses at various vaccine dosages informed the doses used or planned for use in the Phase 2 and 3 clinical trials of the investigational vaccine.
The interim analysis includes results of tests measuring levels of vaccine-induced neutralizing activity through day 43 after the second injection.
References: Lisa A. Jackson et al., “An mRNA Vaccine against SARS-CoV-2 – Preliminary Report”, New England Journal of Medicine, published online July 14, 2020..