A research team of the Japanese government has released results from its first study on a delayed reaction to Moderna's coronavirus vaccine, reported NHK WORLD-JAPAN.

The reaction known as "Moderna arm" is an arm rash or itching appearing more than a week after the vaccine developed by the US firm is administered.

The team examined 1447 Self-Defense Forces personnel who received their first shot nine or more days earlier.

Findings showed that 3.5% of them experienced red blotches on their arms on the ninth day, 4% on the tenth day, and 2.6% on day 11 or later.

Meanwhile, 2.7% of the recipients felt itchiness on their arms on the ninth day, 2.4% on the tenth day, and 1.3% on the eleventh day or later. In one case, the symptom continued until the day 25.

The researchers say people in their 40s are more likely to develop the symptoms.