A cross-sectional, multicenter study of long-term COVID prevalence and risk factors

To date, only one small study has investigated the actual situation of long-term COVID or COVID-19 sequelae in the Japanese population.¹⁹, long COVID is little understood in Japan. Furthermore, to our knowledge, only a few studies have conducted large-scale global surveys of COVID-19 sequelae, and none have examined risk factors for each persistent symptom separately. The duration and severity of each persistent symptom were assessed. We identified sequelae with long-term impact on QOL.

56.1% of study participants had one or more sequelae approximately 1 year (median) post-infection at the time the questionnaire was completed. A report from Italy showed that 87.4% of infected people developed one or more sequelae two months after infection.¹⁶Similarly, reports from China suggested that 76% of infected people had some symptoms that persisted for six months after infection.¹⁸Given the longer duration of symptoms in our study compared to these studies, the slightly lower prevalence of sequelae may be plausible. If not, more than 50% of participants with mild COVID-19 still had one or more sequelae (Table 2). Moreover, the prevalence of long-term COVID was similar in the mild and severe groups, indicating that long-term COVID does not depend on initial disease severity. The distribution of symptoms differed between the acute phase and 1 year after infection. This trend was similar regardless of the severity of COVID-19. Comparing the distribution of sequelae at the time of answering the questionnaire in the mild group and the severe group as a whole, the distribution was the same. Fatigue, alopecia, concentration problems, memory problems, and insomnia persisted in more than 10% of her participants. Previous reports have observed fatigue, cough, congestion, and dyspnea in more than 30% of participants 2-3 weeks after the onset of COVID-19.¹⁵Similarly, studies conducted 4–8 weeks after the onset of COVID-19 found that fatigue, dyspnea, post-traumatic stress disorder (PTSD), anxiety and depression, and concentration problems were more common in intensive care units. persisted in >30% of patients, general ward¹⁷Additionally, in a study of patients six months after COVID-19 onset, fatigue was the most common persistent symptom, persisting in more than 60% of participants, and sleep disturbances and alopecia occurred in 20 of the participants. % or more persisted.¹⁸Consistent with previous studies^{16,twenty two,twenty three}fatigue was the most common persistent symptom in our study. I have.

For the impact of each persistent symptom on QOL, a symptom severity score of 3 to 4 was considered the most influential.In both the mild and severe groups, many participants exhibited severe symptoms of alopecia, concentration problems, memory problems, insomnia, and joint pain (Supplementary Table S2 When S3). The symptoms that appeared strongly in the mild group also appeared strongly in the severe group. In the severe group, cough, expectoration, malaise, dyspnea, anorexia, hyperemia, and diarrhea affected QOL. Thus, the higher the severity of COVID-19, the greater the diversity of sequelae affecting QOL.

Moreno Perez et al.^{twenty two} Risk factors for COVID-19 sequelae were analyzed and no significant risk factors were detected. This may be because the investigators did not consider the risk factors for each symptom individually, so we analyzed the factors associated with each persistent symptom. Persistent sputum production and dyspnea were strongly associated with COVID-19 severity (Fig. 3). Moreover, although the OR of cough was low, he was one of the most common respiratory symptoms of COVID-19 and was associated with disease severity. The more severe the COVID-19, the greater the organic damage it causes to the lungs, and severity may be strongly associated with these respiratory sequelae.Earlier research shows more severe COVID-19 is associated with reduced residual air volume and spread rate¹⁸In addition, people with dyspnea have low forced vital capacity, low forced expiratory volume per second and carbon monoxide diffusing capacity, and restricted ventilation patterns.^{twenty four}High severity, severe acute organic lung injury can result in persistent respiratory symptoms. In addition to respiratory symptoms, chest pain, sore throat, and diarrhea were closely associated with COVID-19 severity and sequelae.Links between gastrointestinal symptoms and COVID-19 may be due to impaired immune system and gut flora^{twenty five}and diarrhea have been previously reported to be associated with COVID-19 severity²⁶Patients with more severe COVID-19 may develop sequelae due to prolonged activation of the immune system and disturbance of the intestinal flora.Myocardial inflammation reported to persist for up to 71 days after COVID-19 and may be associated with long-term chest pain²⁷It is not known if the sore throat is due to Long COVID. Therefore, further studies are needed to explain the direct causal relationship between sequelae diarrhea and sore throat and COVID-19 severity.

Consequences of fatigue, taste disturbance, olfactory disturbance, alopecia, and insomnia were not associated with COVID-19 severity.Fatigue was previously reported not to be associated with COVID-19 severity²⁸Therefore, young people, those without underlying medical conditions, those who have been vaccinated, and those with a history of COVID-19 are at lower risk of developing serious illness, but are more likely to develop these sequelae. may experience. Therefore, it is important to prevent infection until there is a cure for her specific COVID-19 sequelae.

Regarding recovery time from symptoms of fatigue, alopecia and insomnia, it was observed that many patients (more than 50%) did not recover from their symptoms even after being infected with SARS-CoV-2 for over a year. rice field. These symptoms were independent of the severity of his COVID-19, suggesting that even mildly ill individuals may experience long-term sequelae. Therefore, attention should be paid to the sequelae of the Omicron variant of SARS-CoV-2.It is believed to be dominant in 2022, highly contagious and mild^29,30,31.

Our study has some limitations. First, it was a cross-sectional study. Therefore, the time from disease onset to investigation varies among patients, who may be infected with different viral strains or variants. It was not possible to test the infectious strain of each patient.Second, selection bias may affect participants’ willingness to participate, and recall bias may be involved in the severity of sequelae symptoms.³²People with longer COVID-19 are more likely to participate in surveys about the after-effects of COVID-19. Conversely, those without sequelae were likely not interested in the study and, as a result, may not have participated. Accuracy of memory and recall may also vary among participants with acute symptoms. Finally, despite new knowledge about risk factors for COVID-19 sequelae, it is difficult for him to suggest measures to prevent COVID-19 sequelae other than infection prevention and control.

In conclusion, this study revealed a high prevalence of sequelae approximately 1 year after COVID-19. The sequelae of COVID-19, such as fatigue, dysgeusia, olfactory disturbance, alopecia, and insomnia, affect the QOL of even asymptomatic or mildly ill people, and the sequelae are prolonged. Therefore, preventing COVID-19 is important even among individuals who are not at risk of serious illness.