Overall detection of respiratory viruses
One or more viruses were detected in 821/5021 (16.35%) samples before COVID-19, which exhibited a significant decrease in 812/4761 (17.06%) during COVID-19 (Table 1). The total detection rate of the respiratory virus showed a decreasing trend from January to April and an increasing trend from October to December, both before and during the outbreak (Figure.1A).
Prior to and during COVID-19, RSV was the most detected, accounting for 50.79% of positive samples in 2018-2019 and 76.48% in 2020 to 2022. Furthermore, RSV positive rate in 2018-2019 increased more significantly than in 2020 to 2022 (9.38% vs. 13.04%, p < 0.05). Nevertheless, ADV, PIV2 and 3, and Flu B positive rates in 2020 to 2022 reduced more significantly than in 2018 to 2019 (p < 0.05), while Flu A and PIV1 positive rates revealed no significant differences between 2018 to 2019 and 2020 to 2022 (p > 0.05) (Table 1).
As shown in Figure.1B, RSV infections and positive rates exhibited seasonal fluctuations annually between September and May from 2018 to 2019, 2020 to 2021, and 2021 to 2022, whereas they increased sharply in December 2019 to January 2020. ADV infections and positive rates had seasonal fluctuations annually between January 2019 and January 2020, whereas they dropped sharply in April 2020 to January 2022. Flu A infections and positive rates were low between April 2020 and April 2022, while they increased modestly in children during the COVID-19 recovery period from May 2022 to September 2022. Flu B infections and positive rates were low between April 2020 and April 2021, while they increased modestly after July 2021 but were still lower than in the same period before the COVID-19 pandemic. PIV1, 2, and 3 infections decreased after January 2020 (Figure.1C-1H).
Herein, 11 samples detected two viruses, from which 6 specimens were before COVID-19 and 5 during COVID-19 (0.12% vs. 0.10%,p > 0.05). Throughout COVID-19, ADV plus PIV3 detection was the most common mixed infection type, reaching 25.71% of mixed infection samples. However, Neither before nor during COVID-19 were any samples detected more than two viruses.