Moderna is already testing the higher dose in a large Phase III trial, the final stage before seeking emergency authorisation or approval.
Side effects, which included headache, fatigue, body aches, chills and injection site pain, were deemed mainly mild to moderate.
In at least two cases, however, volunteers had severe reactions.
One developed a grade three fever, which is classified as 102.2 degrees Fahrenheit (39°C) or above, after receiving the lower vaccine dose. Another developed fatigue so severe it temporarily prevented daily activities, Anderson said.
Typically, side effects occurred soon after receiving the vaccine and resolved quickly, he said.
“This is similar to what a lot of older adults are going to experience with the high dose influenza vaccine,” Anderson said. “They might feel off or have a fever.”
Norman Hulme, a 65-year-old senior multimedia developer at Emory who took the lower dose of the vaccine, said he felt compelled to take part in the trial after watching first responders in New York and Washington State fight the virus.
“I really had no side effects at all,” said Hulme, who grew up in the New York area.
Hulme said he was aware Moderna’s vaccine employed a new technology, and that there might be a risk in taking it, but said, “somebody had to do it”.