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Survey of recovered patients
Japan's National Center for Global Health and Medicine (NCGM) and other institutions surveyed 457 people in their 20s through 70s who contracted COVID-19 and had recovered by the end of March.
The results showed that over 26 percent suffered from lingering effects, or long COVID, six months after their initial diagnosis or first becoming sick. For nearly 9 percent, the symptoms were continuing one year later.
1. Loss of smell
Nearly 8 percent of the patients reported loss of smell six months after initially developing symptoms. For just over 1 percent, this was still the case one year later.
2. Loss of taste
About 3.5 percent reported loss of taste six months after initially developing symptoms, and 0.4 percent were still experiencing the problem after one year.
About half of the patients said fatigue was one of the first symptoms they experienced during their illness. Nearly 7 percent continued to suffer from lethargy after six months, and about 3 percent after one year.
4. Shortness of breath
About 20 percent said they experienced shortness of breath within one month of initially developing symptoms. About 4 percent were still struggling with their breathing after six months, and 1.5 percent continued to have difficulty after a year.
5. Hair loss
About 10 percent of those surveyed say they experienced hair loss a few months after the onset of infection. About 8 percent continued to suffer from the problem after 100 days. Less than half a percent said they still experienced hair loss after one year.
6. Memory loss, decline in concentration, and depression
About 11 percent of those surveyed said they experienced forgetfulness six months later and 5.5 percent after one year. About 10 percent said they still struggled to focus six months later and nearly 5 percent after one year. Around 8 percent said they suffered from depression six months later and 3.3 percent after one year.
The researchers were unable to find any link between the use of antiviral medication and the presence of prolonged symptoms that might suggest the drugs were responsible.
Differences by gender
The survey found that women are nearly two times more likely to suffer from loss of smell than men, about 1.6 times more likely to suffer loss of taste, about two times more likely to experience prolonged fatigue, and three times more likely to suffer hair loss.
The study also found that patients who are young and weigh less are more likely to suffer from long COVID, even if they only experienced mild symptoms.
Dr. Morioka Shinichiro, an infectious disease specialist at the NCGM, took part in the study. He says the results support previous beliefs that women are more prone to the effects of long COVID than men. But he adds the reasons for this are still unclear.
Morioka added that other reports show the vaccinated are less likely to experience long-term symptoms lasting over 28 days than the unvaccinated. He says this makes it even more important that people get the shots and observe basic anti-infection measures.
Figures accurate as of November 16, 2021.