Prevalence, epidemic trend and risk factors associated with long-term COVID-19 among the general population: two cross-sectional studies in mainland China after the open policy of COVID-19

Background The long-term consequences of the Chinese COVID-19 wave in 2022 remain unknown. To clarify the health outcomes of COVID-19 survivors after the wave of Omicron in 2022 and reveal risk factors of sequelae symptoms. Methods Two cross-sectional studies conducted in August of 2023 and 2024 respectively. A total of 47 827 participants from general population in mainland China. All participants completed an online questionnaire for evaluation of symptoms and characteristics. Results These two surveys included 28718 and 19109 participants, respectively. The corresponding prevalence of long COVID were 62.9% and 65.8% in two surveys, showing a gradual decline over time, with fatigue being the most prevalent symptom. Bing female, aged 18–45 and 46–59, having any chronic diseases or mental disorders, drinking and excessive addiction to electronic devices were positively associated with long COVID (odds ratio > 1, P < 0.05). Conversely, maintaining a regular sleep-wake, combining meat and vegetable diets, consuming vegetables, dairy products, and animal foods daily, sunbathing at least 5 hours per day, having a satisfactory neighborhood relationship and community environment, vaccination significantly reduced the risk of long COVID in 2023 (odds ratio < 1, P < 0.05). Similar results can also be seen in 2024 and different anatomical systems. Conclusions Long COVID remains one of the major health challenges and is influenced by a variety of factors. Monitoring, identifying, and treating risk groups based on relevant factors is of great public health significance.