Research News

Feb 24, 2023

More than half of COVID patients suffer long COVID symptoms

Regardless of SARS-CoV-2 infection severity, there is a risk of residual symptoms including abnormal taste, smell, sleep disturbances, fatigue, and alopecia

More than half of patients suffer long COVID symptoms

A study from Osaka Metropolitan University found that more than half of COVID-19 patients still had residual symptoms, even close to a year afterwards. Symptoms such as fatigue, abnormalities in senses of taste and smell, hair loss, and sleep disorders persisted long after contracting COVID-19, regardless of the severity of the initial infection.

Various long-term effects have been found to occur after infection by the novel coronavirus (COVID-19), and the reality of these lingering symptoms remains unknown. These unknown factors continue to contribute to a general lack of understanding and social unease.

A research group led by Dr. Waki Imoto from the Osaka Metropolitan University Graduate School of Medicine conducted a study at five Osaka hospitals. 285 patients diagnosed with or hospitalized for COVID-19 in 2020, were surveyed to determine the long-term aftereffects.

“At the beginning of 2021, we started research on the aftereffects of COVID-19 through a specialized outpatient clinic that treats people suffering from the aftereffects. We hope that this research will help people understand the aftereffects of COVID-19” said Dr. Imoto.

The results of the survey showed that more than half of the respondents experienced long-term aftereffects, even one year after recovering from their initial COVID-19. The researchers revealed that aftereffects, including fatigue, abnormalities in taste and sense of smell, hair loss, and sleep disorders may persist long after recovering from COVID-19, regardless of the initial infection’s severity.

Even young people, people who are vaccinated, and people who have been previously infected—who are less likely to become severely ill—can still experience these residual aftereffects, making it necessary to continue treating all COVID-19 seriously.

The research results were published online in Scientific Reports on Tuesday, December 27, 2022.


This research was supported by the Osaka Medical Research Foundation for Intractable Diseases, Grant Number 27-2-5.

Paper Information

Journal: Scientific Reports
Title: A cross-sectional, multicenter survey of the prevalence and risk factors for Long COVID
DOI: 10.1038/s41598-022-25398-6
Author: Waki Imoto, Koichi Yamada, Ryota Kawai, Takumi Imai, Kengo Kawamoto, Masato Uji, Hidenori Kanda, Minoru Takada, Yoshiteru Ohno, Hiroshi Ohtani, Manami Kono, Atsuhito Hikiishi, Yosuke Eguchi, Hiroki Namikawa, Tomoya Kawaguchi, Hiroshi Kakeya
Publish: December 27, 2022


Graduate School of Medicine
Waki Imoto
E-mail: wakiimoto[at]
*Please change [at] to @.


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