According to information published online in a medical journal, an experimental COVID-19 vaccine made by Moderna was able to induce an immune response in all volunteers in an early-stage trial.
Initial results, published in The New England Journal of Medicine on Tuesday, showed that the vaccine was generally safe and well tolerated in 45 volunteers, with no serious adverse events.
The study, led by the National Institutes of Health, showed that some antibodies were produced after one dose of the vaccine, but a second dose was needed four weeks later before the volunteers showed a dramatic immune response.
The results were “encouraging and represent an important step forward in the clinical development of mRNA-1273, our candidate for the COVID-19 vaccine,” Moderna CEO Stéphane Bancel said in a statement.
There are still many unknowns about immunity, even if the antibodies really protect against infection and how much protection would be obtained.
Moderna is expected to begin a large-scale study of the vaccine on July 27, a stage three trial that will enroll 30,000 participants at 87 locations. The company’s second stage trial began enrollment in late May.
The main objective of stage three will be the prevention of symptomatic COVID-19. Moderna said key secondary endpoints will include prevention of severe COVID-19 (as defined by the need for hospitalization) and prevention of coronavirus infection.
According to Moderna’s publication on a government website, one group will receive 100 micrograms of the vaccine on the first day and then again on the 29th day. A second group will receive two doses of a placebo to compare.
The initial stage of the trial focused on ensuring that the vaccine was safe in a small population, as well as reducing the dose. The following phases will finally demonstrate their effectiveness in a large population.
Based on results published Tuesday, the most commonly reported systemic adverse events after the second vaccination with the 100 microgram dose were fatigue, chills, headache, and muscle pain, all of which were transient and of mild or moderate intensity.
The study enrolled 45 healthy volunteers ages 18 to 55 at sites in Seattle and at Emory University in Georgia. Trial participants were divided approximately 50-50 between men and women and tested three dose levels of the Modern vaccine at 25, 100 and 250 micrograms.
In an editorial accompanying the article, Penny Heaton, CEO of the Bill & Melinda Gates Institute for Medical Research, said the speed with which Moderna was able to get results was “remarkable,” but cautioned.
“Many phase 3 studies fail due to incorrect identification of the dose that best balances safety and efficacy,” wrote Heaton. “The dosing regimen for this mRNA vaccine is still under study.”
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