key: cord-0815318-k9hpy5dp
authors: Kim, Young-gon; Park, Hyunwoong; Kim, So Yeon; Hong, Ki Ho; Kim, Man Jin; Lee, Jee-Soo; Park, Sung-Sup; Seong, Moon-Woo
title: Rates of Coinfection Between SARS-CoV-2 and Other Respiratory Viruses in Korea
date: 2022-01-01
journal: Ann Lab Med
DOI: 10.3343/alm.2022.42.1.110
sha: 7cbb9db1e1d416ff62858627ed3956fa4148d0db
doc_id: 815318
cord_uid: k9hpy5dp

nan

Dear Editor, While the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed an unprecedented challenge to the global healthcare system, the concern about epidemics caused by other pathogens, such as influenza, is increasing [1] . It is well established that infection with one respiratory pathogen makes a patient vulnerable to secondary infections via several mechanisms, including epithelial damage [2] . As coinfection leads to severe clinical manifestations and longer treatment duration, its risks should be accurately estimated. Previous studies have estimated the coinfection rates of other respiratory pathogens in coronavirus disease (COVID-19) patients [3] [4] [5] [6] [7] . We estimated the coinfection rates of respiratory viruses in COVID-19 patients in Korea.

This study was approved by the Institutional Review Boards [8] . The number of patients included, sample types collected, and types and numbers of coinfecting viruses are described in Table 1 . As both upper and lower respiratory tract samples were available from all patients at NMC and SMC, the total number of samples tested in our study was 748, including 374 each from the upper and lower respiratory tract. The DNA extracted from these samples was stored at 4°C until further use. The average storage duration was 2.8 months (1-5 months). Each sample was tested using the Allplex RV-Essential Assay (Seegene) following the manufacturer's instructions. This assay can detect seven respiratory viruses, including adenovirus, influenza A virus, influenza B virus, metapneumovirus, parainfluenza virus, respiratory syncytial virus, and human rhinovirus.

Adenovirus, human rhinovirus, and metapneumovirus were detected in this study. The coinfection rates determined in the four institutions ranged from 1.3% to 3.3%. Among the 504 patients, coinfection with other respiratory viruses was detected in 11 patients (2.2%). Adenovirus was the most frequently detected coinfecting virus and was detected in six patients. Human rhinovirus and metapneumovirus were detected in four patients and one patient, respectively. Adenovirus was detected in both the upper and the lower respiratory tract samples from one patient, where in other patients, coinfections were detected in only one sample. Furthermore, 1.3% (5/374) and 1.9% (7/374) of upper respiratory tract and lower respiratory tract samples were positive for the coinfection, respectively.

Previous studies have reported viral coinfection rates of 0-6.5% [5] [6] [7] . Frequently coinfecting viruses were respiratory syncytial virus, human rhinovirus, metapneumovirus, parainfluenza virus, influenza virus, and non-SARS-CoV-2 coronavirus. The coinfection rate in our study was within the reported range [5] [6] [7] . However, three factors might have led to an underestimation of the coinfection rate in our study. First, all samples were collected in spring and summer, which follow the outbreak peak of respiratory pathogens, such as seasonal influenza and respiratory syncytial virus. Second, we used a limited target panel due to limited residual sample volumes, which may have contributed to the low coinfection rate, as non-SARS-CoV-2 coronaviruses, which are frequently reported coinfecting viruses in COVID-19 patients [5] [6] [7] , were not included in the panel. Finally, the nucleic acids may have degraded during storage.

The Korea Disease Control and Prevention Agency compared reported infection rates of respiratory viruses before and after the COVID-19 pandemic [9] . According to the report, the influenza infection rate decreased after the pandemic, probably as a result of social distancing, whereas the human rhinovirus infection rate increased. The authors reasoned that it was because human rhinoviruses, as non-enveloped viruses, are resilient to environmental changes and because they have a long shedding period. According to the report, the two most frequently detected non-SARS-CoV-2 respiratory viruses during the pandemic were adenovirus and human rhinovirus, which were the most and second-most frequently identified causes of co-infection, respectively.

As coinfection with other viruses is associated with more severe clinical manifestations in COVID-19 patients, the possibility of coinfection should be carefully considered in COVID-19 patient management [3] . In addition, as COVID-19 and other viral illnesses, such as influenza infection, cannot be distinguished based on clinical manifestations, non-SARS-CoV-2 pathogens should be comprehensively considered in the diagnosis of patients with acute respiratory illnesses [10] .

In conclusion, we evaluated the rates of coinfection with other respiratory viruses in Korean COVID-19 patients in spring and summer 2020 by testing residual samples. Despite the low coinfection rates, the possibility of coinfection should be carefully considered, and appropriate tests should be instantly performed when deemed necessary.

None. 

In preparation for a COVID-19-influenza double epidemic

The airway epithelium: soldier in the fight against respiratory viruses

The microbial coinfection in COVID-19

Rates of co-infection between SARS-CoV-2 and other respiratory pathogens

Co-infection of SARS-CoV-2 with other respiratory viruses and performance of lower respiratory tract samples for the diagnosis of COVID-19

Co-infections of SARS-CoV-2 with multiple common respiratory pathogens in infected patients

Co-infection with other respiratory pathogens in COVID-19 patients

COV-ID-19 molecular testing in Korea: practical essentials and answers from experts based on experiences of emergency use authorization assays

COVID-19 impact on influenza and respiratory viruses surveillance

Co-infections among patients with COVID-19: the need for combination therapy with non-anti-SARS-CoV-2 agents?

 Kim YG and Park H performed the experiments and drafted the manuscript. Kim SY and Hong KH analyzed the data. Kim MJ and Lee JS interpreted the data and contributed to the revision of the manuscript. Park SS and Seong MW supervised the study and performed the final revision of the manuscript.

None declared.