Specific sequelae symptoms of COVID-19 of Omicron variant in comparison with non-COVID-19 patients: a retrospective cohort study in Japan.

BACKGROUND

The specific long-term sequela of coronavirus disease 2019 (COVID-19), also known as long COVID of the Omicron variant remain unclear, due to a lack of cohort studies that include non-COVID patients with cold-like symptoms. The study was conducted to examine specific sequelae symptoms after severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, which is considered the Omicron variant, compared with patients who were never-infected.

METHODS

In this retrospective cohort study, we sent questionnaires in November 2022, targeting those who visited our fever outpatient unit of a single institution from July to September 2022. SARS-CoV-2 infection status was determined by SARS-CoV-2 polymerase chain reaction (PCR) test results during the study period collected in electronic medical records. Clinical characteristics at 30 days or more since the date of SARS-CoV-2 PCR test were assessed by the questionnaires. Multiple logistic regression was performed to investigate the independent association between SARS-CoV-2 infection and possible sequelae symptoms.

RESULTS

In total, valid responses were received from 4,779 patients (mean age: 41.4 years, standard deviation: 19.8 years old). Among them, 3,326 (69.6%) and 1,453 (30.4%) were SARS-CoV-2 PCR test positive and never-infected, respectively. We found that patients with SARS-CoV-2 infection were more likely to have a loss of taste or smell [odds ratio (OR) 4.55, 95% confidence interval (CI): 1.93, 10.71], hair loss (OR 3.19, 95% CI: 1.67, 6.09), neurocognitive symptoms (OR 1.95, 95% CI: 1.43, 2.65), and respiratory symptoms (OR 1.23, 95% CI: 1.03, 1.47) than never-infected patients. SARS-CoV-2 infection was not associated with common cold symptoms, chronic physical distress, or diarrhea as sequelae symptoms. Further, SARS-CoV-2 vaccination showed protective effects on sequelae of loss of taste or smell and hair loss.

CONCLUSIONS

Loss of taste or smell, hair loss, neurocognitive symptoms, and respiratory symptoms were found to be specific sequelae of the SARS-CoV-2 Omicron variant. It is important not to miss these symptoms that follow SARS-CoV-2 infection and to recognize and manage the long COVID.