Doctors have warned that many coronavirus patients, especially younger ones, are suffering aftereffects for a long time despite subsequently testing negative for the virus and are calling on the government to take countermeasures.

The aftereffects include malaise and difficulty breathing. In severe cases, patients became bedridden even though they had been diagnosed with a mild case of the COVID-19 disease caused by the virus.

So far in Japan, there are not many medical institutions that treat patients suffering from such long-lasting effects.

"Most of them are in their 40s or younger. The government needs to take the issue seriously and implement countermeasures," one of the doctors said.

Kaai Akimoto, speaks about the aftereffects she suffers after being infected with the novel coronavirus in an online interview on Jan. 28, 2021. (Kyodo)

Kaai Akimoto, a 30-year-old president of a nursing care company, was diagnosed with the virus in November, and her sense of taste remained lost as of January. "I wonder how long it will last," she said.

She sought the advice of an otolaryngologist who told her, "Nothing can be done." Another doctor prescribed her traditional "kampo" herbal medicine, but her condition did not improve.

Recently, she has a hard time eating because hot food now smells strange to her.

Akimoto has been sharing her experience on Twitter. "There is little information, and many people are scared. I hope I can help people deepen their understanding."

Studies on the long-lasting effects of coronavirus infections are under way in some countries such as Italy and the United States.

In Japan, the National Center for Global Health and Medicine conducted a telephone survey last year on coronavirus patients who had been discharged from hospitals. They collected answers from 63 individuals.

The survey found that in some cases, people continued to experience difficulty breathing, malaise, and olfactory disorders four months after they started showing COVID-19 symptoms.

There were also cases where patients experienced hair loss several months after the disease developed, the center said.

No treatment has been established for long-lasting COVID-19 effects, said Hiroshi Odaguchi, director general of the Kitasato University Oriental Medicine Research Center. "I believe doctors are struggling to respond."

Hiroshi Odaguchi, director general of the Kitasato University Oriental Medicine Research Center, gives an interview on long-lasting effects of the coronavirus disease in Tokyo on Jan. 25, 2021.(Kyodo)

Hirahata Clinic, which has examined about 700 such patients across the country, said 95 percent complained of malaise, while over 80 percent experienced a low mood and reduced thinking ability.

About 30 percent of the patients were in their 40s while nearly 50 percent were in their teens to 30s, the clinic said. The number of women among all patients was 1.4 times that of men.

Koichi Hirahata, head of the clinic, suspects that a "cytokine storm," a severe autoimmune response in which a patient's immune system attacks healthy organs, might be one of the causes of the long-term aftereffects.

He also suspects that women are more likely to suffer the aftereffects than men as they report autoimmune diseases more often.

It is important for people who have recovered from COVID-19 to refrain from exercising for a while, Hirahata said, warning that just taking a walk can cause their condition to deteriorate.

"In one case, a patient became bedridden after exercising forcibly and was dismissed from the workplace," he said. "I want the government to earnestly tackle the problem by taking measures such as letting the public know of the issue so that patients who suffer from the aftereffects will not face disadvantages."