ABSTRACT
Human coronaviruses (HCoVs) are distributed globally and they cause a range of respiratory symptoms. Since HCoV infection usually causes mild upper respiratory tract disease and currently has no specific therapy, there are limited reports on its features, especially in adults. We aimed to evaluate the features of HCoV infections in clinical settings. Adult patients with respiratory symptoms from October 2014 to September 2019 at Nagasaki Genbaku Isahaya Hospital were enrolled. Multiplex reverse transcription-polymerase chain reaction as performed for 15 viruses, including HCoVs, and eight bacterial species on the patients' respiratory specimens. A total of 121 cases were recruited with HKU1, OC43, 229E, and NL63 strains in 80, 21, 12, and 11 cases, respectively. The percentage of HCoV-infected patients peaked in winter (47.5%). Symptoms of fever (69.4%), cough (47.9%), and comorbidities of asthma/cough variant asthma (34.7%) were frequently observed. Lymphocytopenia and increased C-reactive protein levels were observed in laboratory tests. Co-infection with other viruses was identified in 38.8% of the cases. In the repeat-positive cases, 42% were repeat positive within 100 days. HCoV-infected patients showed winter seasonality with a high frequency of comorbidity with asthma and co-infections. Re-infection within an early period was suspected, but further consideration is required.