ABSTRACT
BACKGROUND: Studies have reported coinfection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the cause of coronavirus disease-2019 (COVID-19), with other viruses that cause respiratory tract infections (RTIs). We investigated the coinfection rate of SARS-CoV-2 and other RTI-causing viruses, and whether the cycle threshold (Ct) value of a real-time reverse transcriptase PCR (RT-PCR) differed when the coinfection occurred during the first wave of COVID-19 in Daegu, Republic of Korea, in 2020. METHODS: After performing PCR for SARS-CoV-2, we additionally tested for the presence of RTI-causing viruses to check for coinfection. Subsequently, we identified the specific coexisting respiratory viruses and calculated the coinfection rate. In addition, based on the coinfection status, we compared the Ct values obtained from RT-PCR for SARS-CoV-2 in patients who tested positive for COVID-19 PCR. RESULTS: Of 13,717 patients, 123 had positive results on COVID-19 PCR testing and six tested positive for an RTI-causing virus. Thus, the coinfection rate was 4.9%. There were no statistically significant differences in the mean Ct values of SARS-CoV-2 RT-PCR between coinfected and non-coinfected patients. CONCLUSION: This study computed the coinfection rate of SARS-CoV-2 and RTI-causing viruses and revealed that the mean Ct values in SARS-CoV-2 real-time RT-PCR did not differ according to the coinfection status.