The neutralizing antibodies produced by Moderna Inc.’s vaccine were equivalent to the upper half of what’s seen in patients who get infected and recover, Bloomberg News said.
Meanwhile, the side effects of the vaccine weren’t bad enough to halt the testing process, Bloomberg said, citing results reported by government researchers in the New England Journal of Medicine.
Stimulating the production of antibodies is considered a key milestone in early testing, but doesn’t prove a vaccine will be effective, Bloomberg said.
The test results were based on data involving the first 45 people enrolled in the study, all of whom were 18 to 55 years old.
Results from a second portion of the trial that involved older people weren’t yet available.
A larger, final-stage trial is set to begin on July 27, and will compare results of the vaccine to those of placebo shots given to 30,000 healthy people at high risk of contracting COVID-19.
William Haseltine, a former Harvard Medical School researcher who chairs Access Health International, told Bloomberg that the levels of neutralizing antibodies produced by the vaccine were “respectable” and could possible provide protection against the coronavirus.
But “the jury is out” on the vaccine’s safety, Haseltine added.
More than half of the test subjects who got the middle of three doses suffered mild to moderate fatigue, chills, headache and muscle pain, while 40% experienced a fever after the second vaccination, Bloomberg said.
Three of 14 patients given the highest dose of the vaccine experienced severe side effects, but that dose is not being used in larger trials, Bloomberg said.
Dr. Tony Moody, a researcher at the Duke Human Vaccine Institute, called that “a lot of adverse effects” but told Bloomberg that antibody levels produced by the vaccine were “really encouraging.”
Moderna’s vaccine is among the farthest along in development, and shares in the company jumped 16.4% in after-hours trading Tuesday, Bloomberg said.
The company’s stock price has more than tripled this year based on investor hopes for its coronavirus vaccine.