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

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. 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. 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