Background: The aim of this study is to explore the characteristics of Kawasaki disease (KD) and concurrent pathogens due to a stay-at-home isolation policy during coronavirus disease 2019 (COVID-19) epidemic.

Methods: All patients with KD admitted between February and April in 2015-2020, were classified into before (group 1, in 2015–2019) and after (group 2, in 2020) isolation groups. A total of 4742 patients [with KD (n = 98) and non-KD (n = 4644)] referred to Mycoplasma pneumoniae (MP) and virus detection were analyzed in 2020. Clinical characteristics, laboratory data, and 13 pathogens were analyzed retrospectively.

Results: Group 2 had a significantly increased incidence of KD (0.11%) with 107 patients compared to that of group 1 (0.03%) with 493 patients. The comparisons of oral mucosal change, strawberry tongue, desquamation of the fingertips, cervical lymphadenopathy and neutrophil percentage decreased in group 2 compared to group 1. The infection rate of MP increased significantly in group 2 (34.7%) compared to group 1 (19.3%), while the positive rate of viruses decreased significantly in group 2 (5.3%) compared to group 1 (14.3%). In 2020, the positive rate of MP infection increased significantly in patients with KD compared to the increase in patients with non-KD. The infection rate of MP for younger children aged less than 3 years old was higher in group 2 than in group 1.