Purpose The COVID-19 pandemic has been a psychological burden worldwide, especially for individuals with eating disorders (EDs). In addition, the healthy sisters of patients with EDs are known to present specific psychological vulnerabilities. This study evaluates differences between the general population, patients with EDs, and their healthy sisters. Method A group of 233 participants (91 patients with EDs, 57 of their healthy sisters and 85 community women) was enrolled in an online survey on general and specific psychopathology 1 year after the beginning of the COVID-19 pandemic. The survey examined associations between posttraumatic symptoms and depression, anxiety, obsessive–compulsiveness, interpersonal sensitivity, and eating-related concerns. Results Clinically relevant scores for posttraumatic disorders were found in patients with EDs. Healthy sisters scored similarly to patients for avoidance. Regression analysis showed specific associations between interpersonal sensitivity and posttraumatic symptomatology in patients and healthy sisters, but not in community women. Conclusion The psychological burden in patients with EDs is clinically relevant and linked to interpersonal sensitivity, obsessive–compulsiveness, and global symptom severity. Differences between patients, healthy sisters, and community women are discussed regarding vulnerability factors for EDs. Level of evidence Level III: evidence obtained from well-designed cohort or case–control analytic studies.