The FDA said there were seven “serious adverse events” in the trial, but none of them were fatal.
Four were attributed to the vaccine by trial investigators and Moderna, including intractable nausea and vomiting, facial swelling and rheumatoid arthritis.
Some side effects were hard to shake, though most resolved within a week, the FDA said.
Fewer than six percent reported symptoms persisted for at least a week after getting the shot, but that was similar to the placebo group.
Some of the trial participants had a fever that lasted more than a week.