BACKGROUND: The spinal health of teenagers is adversely affected by the effects of COVID-19, and large-scale scoliosis screening for teenagers after the pandemic has not been reported. This study aimed to explore the prevalence of incorrect posture among Chinese adolescents after the COVID-19 pandemic. METHODS: This was a large-scale cross-sectional study based on school scoliosis screening. Each student underwent visual inspection, Adam's forward bending test, and trunk rotation angle measurement. A scoliometer was used for posture assessment. The participants were subgrouped based on sex, age, and ethnicity to compare the prevalence of suspected scoliosis. Univariate and multivariate logistic regression (LR) models were used to evaluate factors associated with suspected scoliosis. RESULTS: During the post-COVID-19 pandemic period, 1,793,787 students participated. The overall prevalence of incorrect postures among Chinese adolescents was 79.92%, and the most common incorrect postures were high and low shoulders (74.18%) and scapular tilt (70.46%). A total of 97,529 students (5.44%) were suspected to have scoliosis. More females (7.5%) than males (3.7%) and more students aged >
15 years (15.12%) than those aged 10-15 years (7.58%) and <
10 years (0.88%) were suspected to have scoliosis. Univariate LR analysis showed that sex, age, grade, and various incorrect postures were significantly associated with suspected scoliosis. Multivariate LR analysis showed that being female (OR = 2.54, 95% CI: 1.68-3.85), age of 10-15 years (OR = 30.34, 95% CI: 4.99-12.64), and ages of >
15 years (OR = 22.30, 95% CI: 10.84-45.87), and incorrect posture, especially the lumbar eminence and right rib hump were high risk factors for suspected scoliosis. CONCLUSIONS: The prevalence of incorrect posture and suspected scoliosis among Chinese adolescents increased significantly after the COVID-19 pandemic. Early screening of high-risk populations for suspected scoliosis and effective interventions should be implemented to prevent adolescent idiopathic scoliosis during the post-COVID-19 period.