Detection of community-acquired respiratory viruses during COVID-19 pandemic in subtropical region in Japan

Purpose Coronavirus disease 2019 (COVID-19) pandemic changed the dynamics of other community-acquired respiratory viruses (CARVs), however, information regarding the frequency of CARV detection during COVID-19 pandemic in subtropical regions is limited. Additionally, studies comparing the diagnostic accuracy between multiplex and monoplex PCR for the diagnosis of COVID-19 are scarce. Methods We evaluated samples collected from patients suspected of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Okinawa, a subtropical climate in Japan, from March 2020 to March 2021. For SARS-CoV-2, results obtained from monoplex (NIID method) and multiplex (Allplex™ SARS-CoV-2 Assay) PCR were compared. Results In total, 744 samples were collected and 238 viruses were detected in 205 specimens, of which 22 showed viral co-infection. Viral co-infection was more common in patients aged 10 and under than in older patients (p = 0.0054). For CARV, 142 viruses were detected in 127 specimens (17.1%), and human rhinovirus (HRV) was most common. Overall concordance rate for two SARS-CoV-2 assays was 94.1%; 7 and 37 specimens were detected only by NIID and Allplex™ SARS-CoV-2 Assay, respectively. The median cycling threshold values of the 44 samples that were only positive for either the NIID or Allplex™ SARS-CoV-2 Assay were 37.91 for E gene, 38.13 for RdRp/S gene, 38.21 for N gene and 39.16 for N2 gene. Conclusion HRV was continuously detected during COVID-19 pandemic in the subtropical region and viral co-infection was more common in younger patients. For the diagnosis of COVID-19, multiplex PCR was more reliable, especially in samples with low viral load.