Discussion
This is a survey on the recovery after COVID-19 infection, including the symptoms after infection, the impact on psychology and sleep. A total of 1013 Chinese residents were surveyed. The results showed that 91.21% had fever after infection, most respondents had fatigue, muscle and joint pain, sore throat, nasal congestion and runny nose and cough and sputum, Kessel et al. also showed that[13] the symptoms of patients infected with COVID-19 can be divided into physical, mental and social symptoms. Besides, the lingering symptoms of COVID-19 infection can have a significant impact on work and daily functioning. Previous studies have shown that it can take 60 days or longer for some infected people to recover from symptoms.[14, 15] The most common symptoms are fatigue, muscle soreness, etc., and older people, women and people with other diseases have a higher risk of fatigue,[16]in addition, this study also found that cough, expectoration and changes in taste and smell are also the same.
In this survey, the time to turn negative after infection ranged from 2 days to 39 days, 71.27% of the infected people turned negative for about a week, and a small part of them turned negative for more than 20 days. Multiple studies showed that the time from the diagnosis of infection to the negative test was one to two weeks for more than two-thirds of the interviewees. Generally, the virus needed 1-2 weeks to disappear in the body. More severe viruses can take up to six weeks.[17] Regular physical exercise can help prevent infection and reduce infection symptoms,[18] which is consistent with the results of this study.
Cardiopulmonary endurance was significantly lower after COVID-19 infection than before infection, a finding similarly reported by Singh et al. Peak oxygen uptake (VO2peak) was significantly lower in patients who recovered from COVID-19 compared to before infection[19] (70±11% vs 131±45% P < 0.01), and the better the cardiopulmonary endurance level was after infection, there was a significant positive correlation between cardiopulmonary endurance level and the time of negative conversion with the shorter time of negative conversion. Clinton A. et al. found patients infected COVID-19 with poor cardiorespiratory endurance had a higher risk of hospitalization.[20] Therefore, we need to pay more attention to our cardiopulmonary function, people who have not been infected with COVID-19, we should call on them to participate in regular exercise. For people who are experiencing COVID-19 infection or have been infected, it is suggested to reduce unhealthy lifestyle and gradually recover or start their own exercise. We should all improve our awareness of cardiorespiratory endurance and the health benefits it can bring.
Surveys on anxiety show that women are more anxious than men, which may be related to women’s higher psychological susceptibility.[21] Previous studies on SARS survivors have also found women have higher levels of stress, anxiety and depression.[22] There is a significant difference between the number of symptoms of infection and GAD-7 score. The more symptoms there are during infection, the higher the GAD-7 score, that is, the more anxious the infected person will be. A meta-analysis showed that among the patients surveyed, at least one symptom persists, which is a common situation.[23]Therefore, attention needs to be paid to the mental health problems caused by COVID-19 infection, especially for those at risk. Sleep quality was significantly decreased after infection, which, like anxiety, was more significant in women. In a previous survey, sleep quality is also correlated with mental health,[24]which is consistent with the results obtained in this paper.
The survey on regular exercise and sedentary situation showed that 31.49% had regular exercise habits and 39.68% were sedentary people. After COVID-19 infection, 75.32% stopped their original exercise habits, which may be related to the widespread media reports that it is not appropriate to exercise immediately after COVID-19 infection. It can be seen that people’s lives will be more or less changed after COVID-19 infection, and exercise is one of the factors affected. Our research conclusion suggests that the time to turn negative and to decrease fever in sedentary people is significantly longer than that in non-sedentary people, and the time to decrease fever in people who exercise irregularly is significantly longer than that in people who exercise regularly. A study by Chen et al on physical activity and risk of hospitalization for COVID-19[25] shows that sedentary behaviors such as watching TV, this suggests that we should increase physical activity in daily life, reduce sedentary time, and exercise appropriately to improve physical fitness. Other recent studies have shown that low energy expenditure as shown by a higher BMI is highly associated with the risk of hospitalization and severe complications of COVID-19,[26] but our study did not support this view, which may be related to the fact that the population we investigated was patients with mild COVID-19 infection. The benefits of increased physical activity may not end there. Meyer et al. ’s investigation[27] pointed out that maintaining and strengthening physical activity participation and reducing screen time during the COVID-19 pandemic may reduce mental health hazards, and increasing physical activity is an effective strategy to address the physical and mental health risks of the COVID-19 pandemic.[28] This has also been demonstrated at the molecular mechanism level.[29]
In order to properly evaluate the results of this paper, some limitations should be considered. First of all, this study was an anonymous online questionnaire survey, and the respondents were mostly aged 18-25 and highly educated. Second, this survey is a cross-sectional study, lacking follow-up data and using a scale instead of face-to-face interviews, so it can only indicate that the subjects do have anxiety or sleep problems to a certain extent, but medical diagnosis cannot be made. Moreover, the long-term impact of COVID-19 on mental health may come from infection of people around them or socio-economic problems. Follow-up studies are needed to investigate psychological changes. Third, because the online questionnaire survey relies on smart phones, there are relatively few data for teenagers and the elderly. Fourth, the sample size is not large enough, and there may be some correlations between variables that cannot be observed. Fifth, the proportion of women in this survey is also higher than that of men, which makes up for the lack of female data in some previous articles. However, there may be some bias in the study due to the large sample of women. In addition, the subjects of this study were mainly asymptomatic or mildly infected Omicron variants of novel coronavirus, which did not represent the status of patients with severe/critical illness.