Stressful events induce long-term gut microbiota dysbiosis and associated post-traumatic stress symptoms in healthcare workers fighting against COVID-19

•Stress in frontline healthcare workers significantly disrupted the microbial community structure.•We reported for the first time that gut dysbiosis caused by stress in frontline healthcare workers persists for at least half a year.•Frontline healthcare workers exhibited post-traumatic stress in a long-term period.•Some bacteria with anti-inflammatory effects were associated with stress.•Disturbed microbes were essential determinants of the reappearance of post-traumatic stress symptoms in frontline healthcare workers.