Introduction: This study aimed to determine the long-term impact of COVID-19 on childhood asthma and wheezing disorders, which were closely related to viral infections.

Methods: We prospectively recruited paediatric patients admitted to Prince and Wales Hospital between Sept 2016 to Sept 2022. Discharge diagnoses included asthma exacerbation, wheezing illness, and bronchiolitis. Nasopharyngeal aspirate specimens were obtained for the detection of common respiratory viruses through immunofluorescence-based antigen testing and multiplex polymerase chain reaction.

Results: We recruited 1,355 children (male 67.8%) with 1,792 admissions due to wheezing disorders. The mean age (± standard deviation) at first admission was 3.5 ± 3.2 years. Compared with the pre-COVID-19 period (Sept 2016 to Jan 2020), there was a remarkable reduction in wheezing admissions during the pandemic (Feb 2020 to Sept 2022). In particular, admissions due to ?bronchiolitis? dropped from 16 cases per month pre-COVID-19 to 1.4 cases per month during the pandemic, mainly due to decreased RSV infections from 27.8% to 11.4% (p = 0.001). In contrast, rhinovirus (RV) prevailed with a prevalence rate of 65.5%, compared with 45.4% before the pandemic (p < 0.001). A resurge of wheezing admissions mostly caused by RV occurred following the relaxation of local restrictions at the end of 2021.

Conclusions: RV was transmitted more efficiently during the COVID-19 pandemic in children hospitalized with wheezing disorders than other respiratory viruses. Our results indicate a rebound risk of RV infections after easing of the COVID-19 restrictions, highlighting the need for continued surveillance of common respiratory viruses.