Objective: Following the outbreak of the novel coronavirus pandemic, a series of preventive and control measures were adopted by the public, which have had a certain impact on the occurrence of respiratory infectious diseases and changes in their etiology. This article aims to explore the changes in respiratory pathogens among children with respiratory infections during the COVID-19 pandemic and after the comprehensive lifting of restrictions, providing a basis for the clinical diagnosis and treatment of pediatric respiratory infections in the post-pandemic era. Methods: We retrospectively reviewed and analyzed the targeted sequencing results of multiple respiratory pathogens in children with respiratory infections treated at the Children’s Hospital affiliated with Shandong University from January 2022 to December 2023. Results: A total of 16,571 targeted sequencing results of pathogens from children with respiratory infections were included in the analysis (2,810 cases in 2022 and 13,761 cases in 2023). The overall positive detection rates of pathogens in 2022 and 2023 were 95.19% and 96.56%, respectively. The positive detection rates for single pathogens were 16.01% vs. 19.29%, while the rates for two or more pathogens were 79.18% vs. 77.27%. The top three viral pathogens with the highest positive detection rates in both 2022 and 2023 were rhinovirus, parainfluenza virus, and respiratory syncytial virus. In 2023, the top three bacterial pathogens were Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus, whereas in 2022, they were Streptococcus pneumoniae, Haemophilus influenzae, and Bordetella pertussis. The positive detection rates of Haemophilus influenzae, Staphylococcus aureus, Mycoplasma pneumoniae, respiratory syncytial virus, adenovirus, influenza A virus, and rhinovirus in 2023 were significantly higher than those in 2022 (all P < 0.05). However, the positive detection rates of Streptococcus pneumoniae, Bordetella pertussis, and parainfluenza virus were significantly lower in 2023 than in 2022 (all P < 0.001). Differences in the positive detection rates of respiratory pathogens were observed across different age groups. Conclusion: Significant changes in the prevalence of certain pathogens occurred during the COVID-19 pandemic and after the lifting of restrictions. It is essential to strengthen long-term monitoring of common respiratory infectious diseases to guide early clinical intervention.

Background: The global spread of Corona Virus Disease 2019 (COVID-19) has resulted in a significant disease burden, yet asthma patients do not have the expected high morbidity and mortality rates in the pandemics of COVID-19. Objective:To find the difference of angiotensin-converting enzyme 2 (ACE2) in asthma and non-asthma children and evaluate the effect of inhaled corticosteroids (ICS) on its expression. Methods: The ACE2, immunoglobulin E (IgE) and eosinophils were tested in different children. Results: A total of 157 children aged 3-16 years were enrolled. The expression of ACE2 in asthma children were lower than non-asthma children (T=-2.512, P=0.013). Allergic non-asthma children had a significant higher ACE2 expression than children with allergic asthma (P=0.013) and non-allergic asthma (P=0.029). The expression of ACE2 had no significant difference between first diagnosed asthma children and that had been treated with ICS for≥6 months (F=0.028, P=0.598). The allergic asthma children showed a significantly higher Eosinophils cells (EC) count than the allergic non-asthma (W=200, P＜0.001) and non-allergic non-asthma children (W=1089, P＜0.001). Non-allergic asthma children also had a significant higher EC count than the allergic non-asthma (W=182.5, P＜0.001) and non-allergic non-asthma (W= 200.5, P＜0.001) children. There was no significant difference in IgE levels between asthmatic children and non-asthmatic children (W=2792.5, P= 0.18). Conclusion: Circulating ACE2 levels in asthmatic children were lower than those in non-asthmatic children and ICS treatment for ≥6 months did not affect the expression of ACE2 in peripheral blood in the asthma children.