41 - THE IMPACT OF OMICRON VARIANT ON KAWASAKI DISEASE

Background:

Since the onset of coronavirus disease 2019 (COVID-19), Kawasaki disease (KD) incidence has decreased, mainly due to reduced infectious diseases from social distancing measures. Other reasons include guardians and patients avoiding hospitals due to COVID-19 exposure fears, and hospitals limiting admissions via fever screening.

There is no known relationship between COVID-19 and the occurrence of KD, and it is known that a multisystem inflammatory syndrome in children (MIS-C) similar to KD occurs after COVID-19. However, both pediatric COVID-19 on and MIS-C are rare in Japan and Korea, where the incidence of KD is high.

Although the severity of the Omicron mutation has decreased, it is highly contagious and the number of infections in pediatric patients has increased exponentially. We aimed to determine the relationship between prior infection and KD, and between COVID-19 and KD, by evaluating the incidence and characteristics of KD before and after the outbreak of COVID-19 and after the omicron mutation.

Methods:

This retrospective observational study included patients aged < 18 years with acute-phase KD diagnosed between January 2016 and January 2023. The acute phase KD was defined as a primary diagnosis of KD treated with intravenous immunoglobulin (IVIG) therapy. Data were extracted from the Clinical Data Warehouse containing information from eight affiliated university hospitals in Korea. We conducted analysis on changes in the number of patient admissions and clinical characteristics before and after the onset of the COVID-19 pandemic, as well as before and after the period of the Omicron variant.

Results:

A total of 2,077 admissions were included in the analysis. When comparing before and after the COVID-19 pandemic, a significant decrease in the number of admissions with KD was observed (P < 0.001), as previously known. However, when comparing before and after the omicron variant, there was no significant change in the number of admissions (P=0.695). During the Omicron variant period, overall admissions of pediatric patients significantly increased (p=0.020). On the other hand, respiratory and gastrointestinal infections did not significantly increase (P=0.120, P=0.810).  

Conclusion:

After the Omicron variant, COVID19 increased rapidly in pediatric patients and hospital use among pediatric patients increased, but pediatric infectious diseases and KD have not yet increased. This may suggest that the severe acute respiratory syndrome coronavirus 2 is not the antecedent cause of KD. In addition, it is necessary to confirm the relationship between KD and increasing infectious diseases in order to identify preceding infectious agents in the future.