SEATTLE — An investigational vaccine designed to protect against COVID-19 appears safe. In healthy adult volunteers enrolled in a phase 1 trial, the vaccine resulted in the production of neutralizing antibodies, according to interim results published today in the New England Journal of Medicine. The study, detailed in “A SARS-CoV-2 mRNA Vaccine — Preliminary Report,” is being led by Lisa A. Jackson, MD, MPH, a senior investigator at Kaiser Permanente Washington Health Research Institute in Seattle.
“The world urgently needs vaccines to protect against COVID-19,” Dr. Jackson said. “We are glad to be able to contribute to these efforts by initiating the first clinical trial of a COVID-19 vaccine, which was developed, produced, and put into a first-in-human clinical trial in record time.”
The experimental vaccine, mRNA-1273, was designed by researchers at the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, in collaboration with the vaccine manufacturer Moderna Inc. of Cambridge, Massachusetts.
The first volunteer received the first vaccine dose on March 16 at Kaiser Permanente Washington Health Research Institute. The interim report details the initial results of the first 45 volunteers aged 18 to 55 enrolled at the study sites in Seattle and at Emory University in Atlanta. Three groups of 15 volunteers received 2 intramuscular injections, 28 days apart, of 25, 100, or 250 micrograms of the investigational vaccine. All volunteers received the first injection; 42 volunteers received both scheduled injections. In April, the trial expanded to enroll adults older than 55, but the newly published results cover only the group of volunteers aged 18 to 55.
No serious adverse events were reported. Fatigue, headache, chills, muscle aches, and pain at the injection site were reported by more than half of the volunteers, with systemic adverse events being more common following the second injection and in those who received the highest vaccine dose. Data on side effects and immune responses at the 3 different 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 antibodies through day 43 after the second injection. Neutralizing antibodies induced by mRNA-1273 are directed at a portion of a viral “spike” protein that the coronavirus uses to bind to and enter human cells. Two doses of the vaccine prompted production of high levels of neutralizing antibody that were above the average values seen in convalescent serum obtained from people with confirmed cases of COVID-19.
A phase 2 clinical trial of mRNA-1273, sponsored by Moderna, began enrollment in late May, and plans are underway to launch a phase 3 efficacy trial in July 2020.
Additional information about the trial design is available at clinicaltrials.gov using the identifier NCT04283461. This trial was supported in part by NIAID grants UM1AI148373 (Kaiser Permanente Washington) and UM1AI148576 (Emory University). The Coalition for Epidemic Preparedness Innovations provided funding for the manufacture of mRNA-1273 phase 1 material.
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Read more about Kaiser Permanente’s research on vaccines.