We read with interest the article reported by Elda Righi et al. about persistent symptoms after COVID-19.1 Following acute infection, various long-lasting symptoms such as fatigue, headache, cough, and muscle pain are described as “long COVID.”2 The World Health Organization (WHO) and the United States Centers for Disease Control and Prevention (CDC) have given incongruous definitions.3, 4 The prevalence of long COVID varies widely, partly because of variability in definitions, study design, sampling frame, vaccine status, comorbidity, and other factors.5 A study from the United Kingdom revealed that long COVID symptoms lasting more than 4 weeks were reportedly less frequent after Omicron infection (4.5%) than after Delta infection (10.8%).6 The variation of coronavirus also played an essential role in affecting the prevalence of long COVID. We investigated the prevalence and clinical features of long COVID from Omicron infection by searching relevant studies in major databases.