The epidemiological features of pediatric viral respiratory infection during the COVID-19 pandemic in Taiwan

BACKGROUND: Enhanced nonpharmaceutical interventions (NPIs) to prevent the Coronavirus Disease 2019 (COVID-19) have shown various levels of impact on common respiratory pathogens. We aimed to analyze the epidemiological changes seen in certain common respiratory viruses found in Taiwanese children (e.g., influenza virus, enterovirus, parainfluenza virus, adenovirus and respiratory syncytial virus (RSV)) after the implementation of public health measures, as well as interpret the possible meaning of these changes. METHODS: This retrospective observational study examined the viral isolation from children younger than 18 years at a medical center in central Taiwan during the period January 2015–December 2020, a time frame of six years. Viral isolations prior to the COVID-19 pandemic (January 2015–December 2019), along with those during the post-COVID-19 period (January–December 2020) were analyzed and compared. RESULTS: A total of 6899 throat swab samples were collected during the pre-pandemic period of 2015–2019, with 2681 of them having a positive result (38.86%). There were a total of 713 samples collected in 2020, with 142 of them showing positive results (19.92%). The overall positive rate of viral isolates significantly decreased in 2020 (p < 0.001). Declines in the isolation of the influenza virus, parainfluenza virus, adenovirus and enterovirus were observed. The RSV surprisingly became the leading isolate, with up to 47 (6.59%) instances in 2020, and showing an unusual peak in the winter of 2020. The rise began in September of 2020 and reached its plateau in November of that year. CONCLUSIONS: Most respiratory viruses decreased under NPIs regarding SARS-CoV-2. However, the RSV outbreak in the winter of 2020 had shown the limitation of current NPIs. Possible explanations have been discussed in details and public preventive measures should be reinforced for RSV, particularly amongst people having young children both at home and in care centers.