Impact of the COVID-19 pandemic and lockdown measures on clinical visits and subjective symptoms in childhood allergic rhinitis induced by house dust mites in Shanghai.

Background: Establishing the interaction between aeroallergens and air pollution in children with house dust mite induced allergic rhinitis (HDM-AR) remains challenging, especially in urban areas. The coronavirus disease 2019 (COVID-19) pandemic and the subsequent lockdown measures provided a valuable opportunity.

Methods: We analyzed the clinical data of HDM-AR children between March and August in 2018-2020, and classified the children according to the type and the degree of HDM sensitization. The records of patients' hospital visits, allergic rhinitis symptoms assessments, and air pollution measurements in Shanghai were used to assess the differences before (2018-2019) and during the pandemic (2020), as well as during lockdown (March-June) and unlockdown (July-August) period in 2020.

Results: The study included 1570 HDM-AR children aged 2 to 8 years old, 815 (51.9%) were monosensitized to HDM (mono-HDM-AR), and 755 (48.1%) were polysensitized to HDM (poly-HDM-AR). There was a significant increase in the rate of clinical visits among children with HDM-AR during the COVID-19 pandemic compared to pre-pandemic (P < 0.001), particularly among older children aged 7-8 years (P = 0.01). During the unlockdown period, there was a notable decrease in clinical visits for children with poly-HDM-AR (P < 0.001). Children with high levels of HDM sensitization exhibited significant symptom improvement in unlockdown period (P < 0.001). Although the air pollutants concentration had improved during the study, there was no effect on the improvement of HDM-AR children as expected.

Conclusions: The COVID-19 pandemic and its associated lockdown measures provided a unique context to observe the dynamics of management in children with HDM-AR. The findings underscore the complexity of managing allergic conditions in pediatric populations, highlighting the influence of environmental and lifestyle changes on disease presentation and the need for tailored approaches to treatment during periods of societal disruption.