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. Severe acute respiratory infection (SARI) specimens were collected from hospitalized children in Baiyin, China, from 2021 to 2023. 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 using SPSS 26.0 software. A total of 1353 nasopharyngeal swab specimens were collected from children with SARI between 2021 and 2023. The male-to-female ratio of 1.49:1, the total virus detection rate of 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). During the three-year study period, there was no significant difference in the detection rate of pathogen positivity between the ≤ 1 year (OR: 0.986, 95% CI: 0.960–1.013) and 1–3 years (OR: 1.018, 95% CI: 0.997–1.060) age groups (P > 0.05). However, there were significant differences in pathogen positivity rates between 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 (P < 0.05). Significant differences in pathogen positivity rates were observed between male (OR: 1.293, 95% CI: 1.156–1.445) and female (OR: 1.354, 95% CI: 1.157–1.583) children (P < 0.05). The positive detection rates for various viruses showed a decreasing trend in January and February 2023; however, IFV showed a significant rebound in 2023. Following the lifting of COVID-19 control measures, the overall positive detection rate for respiratory viruses increased significantly from 27.84 to 45.03% (OR: 1.313, 95% CI: 1.198–1.438) (P < 0.05). Prior to the lifting of control measures, the ranking of positive detection rates for respiratory viruses in children was as follows: HPIV > HRSV > HADV > HRV > HMPV > EV > HCOV > influenza virus (IFV). After the measures were lifted, the order was as follows: EV > IFV > HADV > HCOV > HPIV > HRV > HMPV > HRSV. The peak detection periods for HRV, HMPV, HADV, and EV shifted to later time points compared to those before the measures were lifted. After the lifting of 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), HCOV (OR: 1.043, 95% CI: 1.017–1.070), and HADV (OR: 1.028, 95% CI: 0.999–1.059) all significantly increased (P < 0.05); HRV (OR: 1.019, 95% CI: 0.994–1.044) and HMPV (OR: 1.010, 95% CI: 0.989–1.032) showed non-significant increases in positive detection rates (P > 0.05); HRSV (OR: 0.965, 95% CI: 0.946–0.985) was significantly reduced (P < 0.05), while the positive detection rate for HPIV (OR: 0.971, 95% CI: 0.943–1.001) showed no significant decrease(P > 0.05). These findings help clarify that social interventions can influence the prevalence of respiratory viruses in children during unique historical periods. The implementation of COVID-19 control measures may have curbed the spread of respiratory viruses in children during the study period. After the lifting of control measures, monitoring of respiratory pathogens must be strengthened to reduce the harm caused by respiratory viruses to children’s health.

Objective: The COVID-19 pandemic significantly affected the transmission of respiratory pathogens worldwide. This study aimed to describe the epidemiological characteristics of respiratory infections among children in Lanzhou, China, during the post-pandemic period and to investigate how meteorological factors influence the transmission of respiratory pathogens in the Lanzhou region. Methods: During the study period, 42.5% of children tested positive for respiratory pathogens (32.8% single, 9.7% mixed infections). Predominant pathogens were influenza virus (IFV, 12.3%), adenovirus (HAdV, 8.2%), rhinovirus (RV, 7.5%), and respiratory syncytial virus (RSV, 6.7%). RSV and IFV peaked in infants <1 year (14.1% and 13.5%), while Mycoplasma pneumoniae (MP) was highest in school-aged children (8.5%). Mixed infections increased with age (2.8% to 11.6%), with no sex differences. Seasonal patterns varied: IFV peaked in winter (26.9%), enteroviruses in summer (18.9%), and RSV showed bimodal winter-spring distribution. IFV negatively correlated with temperature (r = -0.50) and positively with atmospheric pressure (r = 0.37). RSV negatively correlated with temperature (r = -0.49), while MP positively correlated with humidity and pressure.Nonlinear lag modeling showed immediate meteorological effects (0-week lag). IFV showed elevated risk under extreme low temperatures and high pressure (RR: 10.395 and 18.597), though wide confidence intervals warrant caution. HAdV and MP risks increased similarly. Conversely, HPIV and RV showed protective associations at low temperatures or high wind speeds. Wind speed appeared protective against most pathogens, but this observational finding requires interventional validation. Conclusion: Pediatric respiratory pathogen prevalence in Lanzhou exhibited distinct age-dependent and seasonal characteristics, with pathogen-specific meteorological associations. Detection risks for IFV, RSV, HAdV, and MP increased with low temperatures and high pressure, while RV and HPIV showed opposite patterns. The protective wind speed effect suggests ventilation improvements may reduce transmission risk, though this hypothesis-generating conclusion requires further validation. These findings inform age-stratified, seasonally-adapted prevention strategies and meteorological early warning systems.

Objective: Human adenoviruses (HAdVs) are common pathogens causing inflammation in the upper respiratory tract, lungs, conjunctiva, urinary tract, and gastrointestinal tract. They can lead to severe, even fatal infections in immunocompromised patients, representing a significant public health threat. To comprehensively assess the impact of HAdV on public health, this study investigated the epidemiological and genetic characteristics of respiratory adenoviruses in Lanzhou City from 2023 to 2025. Methods: From 2023 to 2025, 1,269 acute respiratory infection specimens were collected from sentinel hospitals in Lanzhou City. HAdV nucleic acids were detected using real-time fluorescent quantitative PCR (qPCR). A portion of HAdV-positive specimens underwent viral isolation using Hep-2 cells. Successfully isolated adenovirus strains were subjected to whole-genome sequencing. Phylogenetic trees were constructed for the HAdV whole genome, Penton base, Hexon, and Fiber genes, and protein variant sites were analyzed. Results: The overall HAdV positivity rate in acute respiratory infection specimens from Lanzhou City was 7.88% (100/1269) from 2023-2025, with a higher positivity rate observed in children aged ≤15 years. HAdV prevalence displayed seasonal variations, with significantly higher positivity rates in autumn and winter (10.83%, 73/674) compared to spring and summer (4.54%, 27/595). Whole-genome sequencing identified the predominant circulating HAdV strain in Lanzhou City during the study period as HAdV-B, all of which were HAdV-3. Phylogenetic analyses of the Penton base, Hexon, and Fiber genes revealed high genetic homology between all nine Lanzhou HAdV-B strains and the Guangzhou candidate vaccine strain (GenBank: DQ099432.4), clustering on the same branch. Furthermore, the Penton base RGD domain and Hexon antigenic epitope of the nine Lanzhou HAdV-B strains remained highly conserved compared to the Guangzhou candidate vaccine strain, showing no significant mutations. Conclusion: The prevalent HAdV strain in Lanzhou City from 2023 to 2025 was type B3. Based on these findings, it is tentatively suggested that the vaccine candidate strain from Guangzhou may provide good immune protection against these prevalent strains, though verification through clinical trials is required.