Background: Non-Pharmaceutical Interventions (NPIs) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) not only curbed the spread of novel coronavirus (COVID-19) but also affected common respiratory viruses infected by children. The purpose of this study was to explore the effect of NPIs on common respiratory viruses in children. Methods: Samples of children diagnosed with respiratory tract infection in Children’s Hospital affiliated with Zhejiang University from January 2019 to August 2023 were collected, and ADV, Flu A, Flu B and RSV were detected. To analyze the changes in common respiratory viruses in children in three stages: pre-COVID-19, pandemic and late. Statistical analysis was carried out with R software. Results: From January 2019 to August 2023, a total of 567,858 samples were tested, including 308,163 males, accounting for 54.26%, and 259,695 females, accounting for 45.73%. Among them, there were 173,956 positive samples (30.63%), 40,279 ADV-positive samples (23.15%), 78,580 Flu A-positive samples (45.17%), 26,888 Flu B-positive samples (15.45%) and 28,209 RSV-positive samples (16.21%). Among children of different ages in Hangzhou before, during and after COVID-19, the highest total detection rate of respiratory virus was 1-3 years old (accounting for 40.24%), followed by 4-6 years old (accounting for 26.59%). The distribution in different seasons shows that the number of children infected with respiratory viruses reaches a peak in winter and spring. Compared with 2019 (35.60%) before the COVID-19 epidemic, the total detection rate of common respiratory viruses in children was lower during the COVID-19 pandemic (2020-2022) (27.89%, 22.71%, 24.63%), and it was increased in 2023 while after NPIs were cancelled (accounting for 33.75%). Conclusion: NPI measures can effectively reduce the spread of common respiratory viruses, but at the same time, they will weaken human immunity to these respiratory viruses.

Nonpharmaceutical interventions (NPIs) against coronavirus disease 2019 (COVID-19) reduced the prevalence of coronavirus among children and influenced the transmission of other viruses. This study investigates the impact of NPIs on human enterovirus (HEV) among children in Hangzhou, China. We collected and analyzed the laboratory results and clinical data of children diagnosed with hand, foot, and mouth disease (HFMD) or herpangina (HA) during the following periods: pre-COVID-19 (January 2019 to December 2019), COVID-19 pandemic (January 2020 to December 2022), and post-COVID-19 (January to August 2023). A total of 38,582 specimens that met the inclusion criteria were enrolled, of which 1,777 (5.58%) tested positive for enterovirus. In comparison to the pre-COVID-19 period, which had 695 (5.63%) HEV-positive specimens, the numbers dramatically decreased to 69 (1.19%), 398 (5.12%), and 112 (1.58%) in 2020, 2021, and 2022, respectively, but significantly increased to 503 (9.00%) in 2023. Seasonal peaks of infections occurred between May and August each year, with positive rates of 10.58%, 25.27%, 31.74%, and 10.97%, respectively. Notably, June and July accounted for half of all cases, with a rate of 57.01%. The difference in the positive rates of HEV infection between males and females was statistically significant (P<0.005), with 5.12% (1,084/21,176) and 4.43% (693/15,629) testing positive, respectively, resulting in a male to female ratio of 1.56:1. Among the same age groups, children aged 3-5 years and 5-7 years had the highest positive rates at 11.03% (342/3,102) and 10.03% (205/2,024), respectively, after synthesizing five years of data. The detection rate of HEV-positive cases increased with age, but after the age of 7, the rate declined. The detected types of HEV indicated that enterovirus 71 (EV-A71) and coxsackievirus A16 (CV-A16) are no longer the two common pathogens causing HFMD and HA. In conclusion, NPIs for COVID-19 are highly effective in reducing the transmission of HEV. However, the relaxation of NPIs results in a resurgence of HEVs, surpassing prepandemic levels. Active awareness and surveillance of the epidemiological characteristics of HEV are essential for preventing, controlling, and managing the development of HFMD and HA, as well as contributing to the development of a multivalent HFMD vaccine.