Background and Objectives: COVID-19 can be serious not only in the acute phase but also after the acute phase and some patients develop ME/CFS. There have been few studies on patients with long COVID in whom ME/CFS was diagnosed by physicians based on standardized criteria after examinations and exclusion diagnosis and not based on only subjective symptoms. The purpose of this study was to elucidate the detailed characteristics of ME/CFS in patients with long COVID. Materials and Methods: A retrospective descriptive study was performed for patients who visited a COVID-19 aftercare clinic established in Okayama University Hospital during the period was from February 2021 to April 2022. Results: Clinical data were obtained from medical records for 281 patients, and 279 patients who met the definition of long COVID were included. The overall prevalence rate of ME/CFS diagnosed by three sets of ME/CFS criteria (Fukuda, Canadian and IOM criteria) was 16.8% (48.9% in male and 51.1% in females). The most frequent symptoms in ME/CFS patients were general fatigue and post-exertional malaise (89.4% of the patients), headache (34.0%), insomnia (23.4%), dysosmia (21.3%) and dysgeusia (19.1%). Dizziness, chest pain, insomnia and headache were characteristic symptoms related to ME/CFS. The male to female ratio in ME/CFS patients was equal in the present study, although ME/CFS was generally more common in women in previous studies. Given that patients with ME/CFS had more severe conditions in the acute phase of COVID-19, the severity of the acute infectious state might be involved in the pathophysiology of ME/CFS. Conclusions: The prevalence rate of ME/CFS and the characteristic sequelae in the long COVID condition were revealed in this study.

The long-term clinical course, prognosis, and optimal management of symptoms and conditions after the acute phase of coronavirus disease 2019 (COVID-19) remain to be elucidated. The purpose of this study was to clarify the characteristics of patients referred to a COVID-19 aftercare (CAC) clinic established at a tertiary academic hospital in Japan. This study was a descriptive case series study. All patients who visited the CAC clinic between February 15 and September 17 in 2021 were included. Patients’ background, chief complaints, and clinical courses after the onset of COVID-19 were described. A total of 87 Japanese patients (median age, 40.0 years; interquartile range [IQR], 26.5-53.0 years; 52.9% women) were referred to the CAC clinic. The median interval between the onset of COVID-19 and the visit to the clinic was 79.0 (IQR, 52.5-112.0) days. Referral sources were hospitals (36 patients), clinics (47 patients), a local healthcare center (3 patients), and other (1 patient). The most common chief complaint was general fatigue (50.4%) followed by dysosmia (28.7%), dysgeusia (26.4%), hair loss (18.4%), headache (17.2%), dyspnea (16.1%), and dyssomnia (13.1%). Respiratory symptoms were common in the early stages of the disease but were less common as the chief complaints when visiting the clinic. On the other hand, neurological, psychiatric, and extremity symptoms were predominant one month after the onset of COVID-19. Regardless of the severity in the acute phase, patients visiting our CAC clinic suffered from a variety of symptoms. General physicians skilled in using a comprehensive approach would be optimal to see patients with such complex symptoms.

The pathogenesis and prognosis of post COVID-19 condition have remained unclear. We set up an outpatient clinic specializing in long COVID in February 2021 and we have been investigating post COVID-19 condition. Based on the results of our earlier study showing that “general fatigue” mimicking myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is the most common symptom in long COVID patients, a retrospective analysis was performed for 39 male patients in whom serum free testosterone (FT) levels were measured out of 61 male patients who visited our clinic. We analyzed the medical records of the patients’ backgrounds, symptoms and laboratory results. Among the 39 patients, 19 patients (48.7%) met the criteria for late-onset hypogonadism (LOH; FT < 8.5 pg/mL: LOH group) and 14 patients were under 50 years of age. A weak negative correlation was found between age and serum FT level (r = −0.301, p = 0.0624). Symptoms including general fatigue, anxiety, cough and hair loss were more frequent in the LOH group than in the non-LOH group (FT ≥ 8.5 pg/mL). Among various laboratory parameters, blood hemoglobin level was slightly, but significantly, lower in the LOH group. Serum level of FT was positively correlated with the levels of blood hemoglobin and serum total protein and albumin in the total population, whereas these interrelationships were blurred in the LOH group. Collectively, the results indicate that the incidence of LOH is relatively high in male patients, even young male patients, with post COVID-19 and that serum FT measurement is useful for revealing occult LOH status in patients with long COVID.

Objective: The most common symptom of post-acute coronavirus disease 2019 (COVID-19) is fatigue, and it potentially leads to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS); however, a specific prognosticator is lacking. We aimed to elucidate the clinical characteristics of patients who developed ME/CFS after COVID-19. Methods: In this retrospective observational study, patients who visited Okayama University Hospital for long COVID between February 2021 and March 2022 were investigated. Results: Of the 234 patients, 139 (59.4%) had fatigue symptoms. Fifty patients with fatigue symptoms (21.4%) met the criteria for ME/CFS (ME/CFS group), while the other 89 patients did not (non-ME/CFS group); 95 patients had no fatigue complaints (no-fatigue group). Although the patients’ backgrounds were not significantly different between the three groups, the ME/CFS group presented the highest scores on the self-rating symptom scales, including the Fatigue Assessment Scale (FAS), EuroQol, and the Self-Rating Depression Scale (SDS). Furthermore, serum ferritin levels, which were correlated with FAS and SDS scores, were significantly higher in the ME/CFS group (193.0 μg/L, interquartile range (IQR): 58.8–353.8) than in the non-ME/CFS group (98.2 μg/L, 40.4–251.5) and no-fatigue group (86.7 μg/L, 37.5–209.0), and a high serum ferritin level was prominent in female patients. Endocrine workup further showed that the ME/CFS group had higher thyrotropin levels but lower growth hormone levels in serum and that insulin-like growth factor-I levels were inversely correlated with ferritin levels (R = −0.328, p < 0.05). Conclusions: Serum ferritin level is a possible predictor of the development of ME/CFS related to long COVID, especially in female patients.

Background and Objectives: Changes in post COVID-19 condition (PCC) characteristics caused by viral variants have yet to be clarified. We aimed to characterize the differences between clinical backgrounds and manifestations in long COVID patients who were infected with the Delta variant and those who were infected with the Omicron variants. Materials and Methods: This study was a single-center retrospective observational study for patients who visited our COVID-19 aftercare outpatient clinic (CAC) established in Okayama University Hospital (Japan) during the period from 15 February 2021 to 15 July 2022. We classified the onset of COVID-19 in the patients into three groups, the preceding, Delta-dominant, and Omicron-dominant periods, based on the prevalent periods of the variants in our prefecture. Results: In a total of 353 patients, after excluding 8 patients, 110, 130, and 113 patients were classified into the preceding, Delta-dominant, and Omicron-dominant periods, respectively. Patients infected in the Omicron-dominant period had significantly fewer hospitalizations, milder illnesses, more vaccinations and earlier visit to the CAC than did patients infected in the Delta-dominant period. Patients infected in the Omicron-dominant period had significantly lower frequencies of dysosmia (12% vs. 45%, ** p < 0.01), dysgeusia (14% vs. 40%, ** p < 0.01) and hair loss (7% vs. 28%, ** p < 0.01) but had higher frequencies of fatigue (65% vs. 50%, * p < 0.05), insomnia (26% vs. 13%, * p < 0.05) and cough (20% vs. 7%, ** p < 0.01) than did patients infected in the Delta-dominant period. Conclusions: The transitional changes in long COVID symptoms caused by the two variants were characterized.

Background: Various symptoms persist even after the acute symptoms in about one third of patients with COVID-19. In February 2021, we established an outpatient clinic in a university hospital for patients with long COVID and started medical treatment for sequelae that persisted one month or more after infection. Methods: To determine the key factors that affect the onset and clinical course of sequelae, a retrospective analysis was performed at Okayama University Hospital (Japan) between February and July 2021. We focused on changes in the numbers of symptoms and the background of the patients during a three-month period from the first outpatient visit. We also examined the relationship with SARS-CoV-2 antibody titers. Results: Information was obtained from medical records for 65 patients. The symptoms of sequelae were diverse, with more than 20 types. The most frequent symptoms were general malaise, dysosmia, dysgeusia, sleeplessness, and headache. These symptoms improved in about 60% of the patients after 3 months. Patients who required hospitalization and had a poor condition in the acute phase and patients who received oxygen/dexamethasone therapy had higher antibody titers at the time of consultation. Patients with antibody titers ≥200 U/mL showed significantly fewer improvements in long COVID symptoms in 1 month, but they showed improvements at 3 months after the first visit. Conclusion: Long COVID symptoms were improved at 3 months after the initial visit in more than half of the patients. Serum antibody titers were higher in patients who experienced a severe acute phase, but the serum antibody titers did not seem to be directly related to the long-term persistence of long COVID symptoms.