Kawasaki disease before and during the COVID-19 pandemic: a single-center comparative study in Switzerland

Background: Kawasaki disease is a rare systemic inflammatory syndrome that mainly affects children under five years of age and is the first cause of pediatric acquired cardiovascular disease. The pathogenesis is complex and a viral trigger is suspected, as well as genetic susceptibility. Multiple studies around the world have shown a decrease in the incidence of Kawasaki disease and have hypothesized that the different sanitary measures enforced in each country during the pandemic period could be responsible to a certain extent. The aim of this study is to evaluate the effects of the COVID-19 pandemic on the disease's incidence, defining characteristics, coronary artery outcomes and management in a tertiary center in Switzerland.

Methods: This study is a retrospective analysis of children who have been diagnosed with Kawasaki disease that compares clinical, laboratory, SARS-CoV-2 exposure, and echocardiographic data as well as treatments before (January 1st 2017 to February 24th 2020) and during (February 25th 2020 to December 31st 2022) the COVID-19 pandemic in Switzerland. Statistical significance of differences in the compared parameters was assessed.

Results: Of the 90 patients included, 31 belonged to the first group and 59 belonged to the second group. There was a statistically significant (p < 0.05) increase in incidence during the pandemic period (5.91/100,000 children) of 88% compared to the pre-pandemic period (3.14/100,000 children). A lesser seasonal variation was observed during the pandemic. 30% of the patients in the pandemic group had an exposure to SARS-CoV-2. There was no other notable difference in demographic factors, clinical presentation, coronary outcome or administered treatment.

Conclusions: To the best of our knowledge, this is the first prolonged European study comparing Kawasaki disease before and during the COVID-19 pandemic. There was a significant increase in incidence in Kawasaki disease during the COVID-19 pandemic. In contrast, studies done in Japan, South Korea and the USA have shown a decrease in incidence. Differences in methodologies, genetics, ethnicities, environments, microbiome-altering behaviors, sanitary measures and SARS-CoV-2 spread are factors that should be considered. Further studies analyzing the differences between countries with increased incidence of Kawasaki disease could help better understand the relevance of such factors and provide more insight into the etiologies of this particular disease.