BACKGROUND: Persistent somatic symptoms brought by COVID are a matter of concern. Post-traumatic stress symptoms (PTSS) and perceived stress have been recognized as risk factors for somatic symptoms. Recently, the associations between social media use and COVID-related PTSS have also been noticed. However, the pathways these factors contribute to persistent somatic symptoms after COVID remain unclear. This study aims to investigate the role of perceived stress as a mediator in COVID-related PTSS and somatic symptoms, and whether social media use moderated the mediation in a sample of healthcare workers (HCWs) during the subacute phase of COVID in the context of the end of China's dynamic zero-COVID policy. METHODS: Questionnaire data from 2281 Chinese HCWs were included in the study. COVID-related PTSS, perceived stress, and somatic symptoms were measured, and a moderated mediator model was developed. RESULTS: The effect of COVID-related PTSS on somatic symptoms was partially mediated by perceived stress. Moreover, social media use positively moderated the relationship between COVID-related PTSS and perceived stress. That is, at higher frequencies of social media use, COVID-related PTSS played a stronger role in perceived stress. CONCLUSION: Our findings suggest that perceived stress and frequency of social media use play a facilitating role in the impact of COVID-related PTSS on somatic symptoms. From a psychosocial perspective, this study identifies psychological interventions targeting stress and benign media communication as potential interventions for persistent somatic symptoms after COVID infection and prevention of long-term COVID.