Objectives To understand the sequelae of COVID‐19. Methods We followed up 1174 patients with severe coronavirus disease 2019 (COVID‐19)who were recovered and discharged for 6 months. Results There were 175 cases with clear IgG results 6 months after discharge, of which 82 (46.9%) were IgG (+) and 16 (9.1%) were IgG (dim+). Four hundred and forty‐one participants (55.4%) had some kind of sequelae. The most common symptoms were fatigue (25.3%), sleep disorder (23.2%) and shortness of breath (20.4%). In those who had sequelae, 262 (59.4%) had more than one symptom. Critical cases were more likely to have cough (20.5% vs 11.6%, p = 0.023) and hypomnesis (15.1% vs 8.0%, p = 0.041) than severe cases. Furthermore, univariate and multivariate logistic regression analyses revealed that women are more likely to have multiple symptoms ( p = 0.002), fatigue ( p = 0.009) and sleep disorder ( p = 0.008), whereas critical illness was found as independent risk factor for hypomnesis ( p = 0.045). Conclusion Our study demonstrated the duration of antibody and sequelae of COVID‐19 and compared the differences amongst different populations.