Although respiratory symptoms were predominant in patients infected with COVID-19, gastrointestinal symptoms were always reported in about 10% patients. Previous studies demonstrated that the SARS-CoV-2 virus still persists in stool samples for a long time after initial infection. Moreover, some patients had a longer duration of COVID-19-related gastrointestinal symptoms, which was defined as "post-acute COVID-19 syndrome".

Previous studies have shown that functional gastrointestinal disorders may occur after acute gastroenteritis. Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders. FD was reported to be correlated with multiple pathophysiological mechanisms, including GI bacterial imbalance, disordered gut microbiota, and disturbed barrier and immune function. It is unknown whether COVID-19 infection could exacerbate the symptoms of FD. Therefore, we followed up a group of FD patients before and after COVID-19 and investigate the impact of COVID-19 infection on the symptoms of FD.

Inclusion Criteria:

1. aged ≥18 years old
2. Patients who met broad criteria of dyspepsia before infection

Exclusion Criteria:

1. organ failure defined by Marshall standard
2. severe psychiatric illnesses
3. suspected or identified bowel obstruction
4. known malignancy
5. pregnancy or lactation
6. unable to provide consent

Patients aged ≥ 18 years old who met broad criteria of dyspepsia were eligible for our study before infection.