Variant-specific symptoms after COVID-19: a hospital-based study in Hiroshima.

BackgroundSymptoms after COVID-19 recovery by SARS-CoV-2 strains are unspecified.MethodsThis self-administered questionnaire-based study was conducted to investigate symptoms after COVID-19 recovery at one of the main hospitals for COVID-19 treatment in Hiroshima, Japan, from September 2020 to March 2022 for patients who visited follow-up consultations after COVID-19. Study subjects were divided into four groups (Wild-type, Alpha, Delta, and Omicron periods) according to COVID-19 onset date. Hierarchical cluster analysis was performed to determine symptom clusters and investigate risk factors for each symptom cluster using multivariate analysis.ResultsAmong 385 patients who enrolled in this study, 249 patients had any persistent symptoms at a median of 23.5 [IQR, 20-31] days after COVID-19 onset. Among patients with any persistent symptoms, symptom clusters including olfactory or taste disorders, respiratory symptoms, and cardiac symptoms were found. Respiratory symptoms were more frequent among patients infected in the Omicron period compared to the Wild-type period (AOR, 3.13; 95% CI, 1.31-7.48; p=0.0101). Compared to patients who recovered from mild COVID-19, patients who needed for oxygen or ventilation support suffered fewer post-COVID-19 respiratory symptoms (AOR, 0.46; 95% CI, 0.22-0.97; p=0.0415) but more post-COID-19 cardiac symptoms among them (AOR, 2.67; 95% CI, 1.26-5.65; p=0.0103). Olfactory or taste disorders were fewer among patients infected in the Omicron period compared to the Wild-type period (AOR, 0.14; 95% CI, 0.04-0.46; p=0.0011).ConclusionThis study revealed that symptoms after COVID-19 may vary depending on the infected strain.