Japanese researchers have released the results of a study of potential side effects from the Moderna vaccine for the coronavirus.
The health ministry team monitored around 1,400 Self-Defense Forces members after they received their first shot.
It found that joint pain was the most commonly observed side effect. Sixty-three percent of participants experienced this reaction on the day they received the shot, while 86 percent complained of it on the following day, and 68 percent two days after the shot.
Fatigue was reported by 13 percent of people on the first day, by 22 percent the following day, and by 16 percent two days later.
One percent of the vaccine recipients developed a fever of 37.5 degrees Celsius or higher on the first day. Four percent reported a fever on the second day, and 2 percent on the third.
The researchers concluded that adverse reactions are most frequently experienced on the day after the shot is given and tend to subside after three days.
They also say young people, particularly those in their 20s, are more likely to develop symptoms such as fatigue and fever.
Visiting Professor Ito Suminobu at Juntendo University’s medical school says young people tend to have a stronger reaction to the dose. He also says people should be prepared for more adverse reactions after the second shot.