Researchers in Japan say the percentage of people who develop aftereffects from the coronavirus Omicron variant is about one-tenth of the level among those infected with other variants.

The group interviewed 53 people in their 20s to 80s who had been hospitalized by early February after contracting the Omicron variant to learn in detail what kinds of aftereffects they experienced.

It then compared their findings with data on people who had been infected with other variants, including Alpha and Delta, that had spread before Omicron.

The group says one in 18 people who were infected with Omicron suffered from fatigue for at least two months, while 10 in 18 people who contracted other variants had aftereffects for two months or longer.

But the group says despite the outcome of its study, many people may suffer from aftereffects after contracting Omicron, because the variant has been infecting far more people.

Morioka Shinichiro of the National Center for Global Health and Medicine says his group made an important discovery. But he says the group could study only a limited number of people and has yet to find out the difference in condition and duration. He expresses his hope for cooperation from more people for a more accurate analysis.