A Rise in Kawasaki Disease Associated with Concurrent Mycoplasma pneumoniae in Suzhou City of East China During the COVID-19 Pandemic: An Observational Cohort Study

Background: Kawasaki disease (KD), currently known as an immune inflammatory cascade triggered by one or more unknown pathogens, is the most common cause of acquired heart disease in children in developing countries. Kawasaki-like disease was rising at the Italian epicenter of the Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In contrast, in Suzhou city, east China, viral transmission and environmental exposure were both contained due to a stay-at-home isolation policy during the SARS-CoV-2 epidemic. In this study, we aimed to determine the potential pathogen triggering KD. Methods: All patients with KD admitted to the Soochow Children’s Hospital in Suzhou of east China, between February 1 and April 30 in 2015-2020, were classified into before (group 1, in 2015-2019) and after (group 2, in 2020) isolation. Clinical characteristics, laboratory data, and a total of 13 pathogens, including Mycoplasma pneumoniae (MP), common respiratory viruses and rotavirus, were retrospectively analyzed and compared. Findings: A total of 600 patients with KD were enrolled. Group 2 had a significantly increased incidence of KD (0.11%) with 107 patients than group 1 (0.03%) with 493 patients. The frequency of MP positivity was increased in group 2 (34.7%, 34/98) vs . group 1 (19.3%, 81/420) ( P = 0.0015). The percentage of patients positive for viruses was decreased in group 2 (5.3%, 4/76) vs . group 1 (14.3%, 61/428) ( P = 0.04).The odd ratio of MP infection in patients with KD is 2.64 (95%CI: 1.898-7.969), indicating that MP infection is 2.64 times more likely to have KD than uninfected patients. Interpretation: Concurrent MP infection has a close simultaneous association with the increased incidence of KD, which may contribute to trigger the pathogensis of KD under the condition of decreased incidence of virus infection due to a stay-at-home isolation policy during the COVID-19 pandemic. Funding Statement: This work was supported by the grants from the National Natural Science Foundation of China (No.81870365 and 81970436), the Natural Nature Science Foundation for Youth (No.81800437), the Jiangsu Provincial Medical Young Talents (QNRC2016756 and QNRC2016764), the Shanghai Science and Technology Support Project for Medicine (No.18411967300). Declaration of Interests: Authors declare that they have no conflict of interest. Ethics Approval Statement: The study was approved by the Ethics Committee of the Children’s Hospital of Soochow University.