A Japanese government survey has shown that about 14 percent of people who had moderate or serious COVID-19 were suffering from aftereffects even a year later.

A team led by Kochi University Professor Yokoyama Akihito reported its survey results to a health ministry panel on Wednesday.

The survey targeted over 1,000 people nationwide who were admitted to hospitals between the roughly one-year period ending in September after developing moderate or severe virus symptoms.

The team checked every three months whether the former patients had any symptoms considered as virus aftereffects after leaving the hospital.

The results showed that overall, the number of people who complained of such symptoms continued to fall as time passed. But 13.6 percent of the respondents had at least one type of symptom even a year after they were first diagnosed with COVID-19.

The results also showed 9.3 percent complained of declining muscular strength, 6 percent said they had difficulty breathing and 4.9 percent mentioned fatigue.

Yokoyama said those who had severe COVID-19 respiratory symptoms appear more likely to suffer from aftereffects. He said it is important to identify factors responsible for lingering aftereffects.

Another government team led by Keio University also reported its survey results at the panel meeting. The survey was conducted on more than 1,000 people who had developed mild to severe virus symptoms through February last year.

The results showed that a year after receiving their first diagnosis, 12.8 percent of them complained of fatigue and 8.6 percent said they had difficulty breathing. Those who complained of declining muscular strength and impaired concentration each made up 7.5 percent.