Results from an early safety study of Moderna Inc’s coronavirus vaccine candidate in older adults showed that it produced virus-neutralizing antibodies at levels similar to those seen in younger adults, with side effects roughly on par with high-dose flu shots, researchers said on Tuesday.

The study published in the Journal of Medicine offers a more complete picture of the vaccine’s safety in older adults, a group at large risk of critical impediment from COVID.

Dr. Evan Anderson is one of the study’s lead researchers from Emory University in Atlanta said,  the findings are encouraging because immunity tends to weaken with age.

The first trial conducted in individuals aged 18-55, this study was an extension of Moderna’s Phase I safety trial.

Moderna’s vaccine tested two doses of 25 micrograms and 100 micrograms in 40 adults.

The team found that in older adults who received two injections of the 100 microgram dose 28 days, the vaccine produced immune responses similar to those which are seen in younger adults.

In the final stage before seeking emergency authorization or approval, Moderna is already testing the higher dose in a large Phase III trial.

Side effects, which included headache, fatigue, body aches, chills, and injection site pain, were judge mild to moderate.

However, volunteers had severe reactions, in at least two cases.

After receiving the lower vaccine dose, one developed a grade three fever, which is classified as 102.2 degrees Fahrenheit or above. Anderson said, another developed exhaustion so severe it temporarily prevented daily activities.

Normally, side effects occurred soon after receiving the vaccine and resolved quickly, he said.

Anderson said, “This is similar to older adults who are going to experience with the high-dose influenza vaccine.” 

Norman Hulme senior multimedia developer at Emory who took the lower dose of the vaccine said he felt forced to take part in the trial after watching first responders in New York and Washington State fight the virus. “I had no side effects at all.”

Hulme said he was enlightened Moderna’s vaccine uses new technology, and there might be a risk in taking it, but “somebody had to do it.”

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