Dynamics of respiratory virus transmission in children during and after COVID-19 outbreak control in Baiyin, China

Purpose We aimed to study the changes in respiratory virus detection rates during the control of the COVID-19 outbreak and to elucidate possible epidemiologic disturbances after the lifting of control measures. Methods Severe acute respiratory infection (SARI) specimens in hospitalized children were collected from 2021-2023 in Baiyin, China. We conducted real-time fluorescence quantitative PCR (RT-qPCR) to detect various respiratory viruses, including influenza virus (IFV), human respiratory syncytial virus (HRSV), human rhinovirus (HRV), human parainfluenza virus (HPIV), human metapneumovirus (HMPV), human adenovirus (HADV), enterovirus (EV), and human coronavirus (HCoV). The results were statistically analyzed by SPSS 26.0 software. Results A total of 1353 nasopharyngeal swab specimens were collected from children with acute respiratory tract infections (ARTIs) between 2021 and 2023. The male-to-female ratio was 1.49:1 and the overall viral detection rate was 33.85% (458/1353). Data were analyzed by comparing two distinct periods: before the lifting of the COVID-19 control measures (January 1, 2021 –December 6, 2022) and after the lifting of the control measures (December 7, 2022 – December 31, 2023). No statistically significant difference was observed in pathogen-positive detection rates between periods with and without control measures for the age groups ≤1 year (OR: 0.986, 95% CI:0.960-1.013) and 1-3 years (OR: 1.018, 95% CI:0.997-1.060). However, significant differences were found in the 3-6 years (OR:1.097, 95% CI:1.049-1.146) and >6 years (OR:1.099, 95%CI: 1.063-1.138) age groups, as well as in males (OR:1.293, 95%CI:1.156-1.445) and females (OR: 1.354, 95%CI:1.157-1.583). The overall positive detection rate of respiratory viruses increased significantly from 27.84% to 44.84% (OR:1.313, 95% CI:1.198-1.438) after the lifting of COVID-19 control measures. Before the lifting of control measures, the order of respiratory virus-positive detection rates in children was human parainfluenza virus (HPIV) > human respiratory syncytial virus (HRSV) > human adenovirus (HAdV) > human rhinovirus (HRV) > human metapneumovirus (HMPV) > enterovirus (EV) > human coronavirus (HCoV) > influenza virus (IFV). After lifting the control measures, the order was EV > IFV > HAdV > HCoV > HPIV > HRV > HMPV > HRSV. Compared with the period before lifting the control measures, a rightward shift in the peak detection time period was observed for HRV, HMPV, HAdV, and EV. After lifting the control measures, the positive detection rates of IFV (OR:1.090, 95%CI:1.059-1.122), EV (OR:1.102, 95%CI:1.064-1.141), and HCoV (OR:1.043, 95%CI:1.017-1.070) increased significantly. A significant decrease was seen in the positive detection rate for HRSV (OR:0.965, 95%CI:0.946-0.985); and a non-significant decrease in the positive detection rate for HPIV (OR:0.971, 95%CI:0.943-1.001).and no significant difference was seen in the positive detection rate for HMPV (OR:1.019, 95%CI:0.989-1.032).and HADV (OR:1.028, 95%CI:0.999-1.059).Notably, influenza virus rebounded significantly between January and February 2023. Conclusions These findings help elucidate that social interventions can influence the prevalence of childhood respiratory viruses during a unique historical period. The implementation of the COVID-19 outbreak control measures may have curbed the spread of childhood respiratory viruses. Surveillance of respiratory pathogens must be strengthened after control measures are lifted to reduce the risk of respiratory viruses affecting children's health.