Prevention Measures for COVID-19 and Changes in Kawasaki Disease Incidence

Abstract

Background: Kawasaki disease is suspected to be triggered by previous infection. The prevention measures for coronavirus disease 2019 (COVID-19) have reportedly reduced transmission of certain infectious diseases. Under these circumstances, the prevention measures for COVID-19 may reduce the incidence of Kawasaki disease.

Methods: We conducted a retrospective study using registration datasets of patients with Kawasaki disease who were diagnosed in all 11 inpatient pediatric facilities in Yamanashi Prefecture. The eligible cases were 595 cases that were diagnosed before the COVID-19 pandemic (from January 2015 through February 2020) and 38 cases that were diagnosed during the COVID-19 pandemic (from March through November 2020). Incidence of several infectious disease were evaluated using data from the Infectious Disease Weekly Report conducted by the National Institute of Infectious Diseases.

Results: Epidemics of various infectious diseases generally remained at low levels during the first 9 months (March through November 2020) of the COVID-19 pandemic. Moreover, the incidence of COVID-19 was 50-80 times lower than the incidence in European countries and the United States. The total number of 38 cases with Kawasaki disease for the 9 months during the COVID-19 pandemic was 46.3% (-3.5 standard deviations [SDs] of the average [82.0; SD, 12.7 cases] for the corresponding 9 months of the previous 5 years. None of the 38 cases was determined to be triggered by COVID-19 based on their medical histories and negative results of severe acute respiratory syndrome coronavirus 2 testing at admission.

Conclusion: These observations provide a new epidemiological evidence for the notion that Kawasaki disease is triggered by major infectious diseases in children.

Keywords: COVID-19; Kawasaki disease; infectious disease; retrospective database.

Figure 1.. Epidemiologic features of Kawasaki disease in Yamanashi and Japan.

The bars indicate the incidence rate (per 100,000 children aged 0–4 years/year) in the Yamanashi study (2007–19), and the solid line indicates that in the nationwide survey (2007–18). Nationwide data for 2019 were unavailable at the time of manuscript preparation (January 2021).

Figure 2.. Epidemics of COVID-19 in Yamanashi (A) and Japan (B). The horizontal axis shows calendar weeks in 2020. The closed bars (left vertical axis) show numbers of weekly diagnosed cases. The solid lines (right vertical axis) show the cumulative number of cases. The open bars show numbers of pediatric (aged less than 14 years) cases in Yamanashi. COVID-19, coronavirus disease 2019.

Figure 3.. Epidemics of infectious diseases in 2020 season. Epidemics of influenza (A), hand-foot-and-mouth disease (B), RSV infection (C), and roseola infantum (D) in Yamanashi and Japan, based on the Infectious Disease Weekly Report (IDWR) conducted by the National Institute of Infectious Diseases (NIID). The vertical axes show the cumulative numbers of cases for the 9 months from March through November reported by sentinel centers in Japan (left axis) and Yamanashi (right axis). In each panel, the left pair of bars with ranges show average numbers with SD in the previous 7 years (2013–19), while the middle and right pairs of bars show the cumulative numbers of cases in the 2019 and 2020, respectively. Black bars: Japan. Gray bars: Yamanashi. RSV, respiratory syncytial virus; SD, standard deviation.

Figure 4.. Epidemiologic features of Kawasaki disease in 2020 in Yamanashi. (A) Statistical process control chart of monthly changes in the number of cases. The dotted sequential line shows the average of monthly cases in the previous 5 years (2015–19). The closed bars indicate the number of monthly cases from December 2019 through November 2020. The solid and dotted straight lines indicate the mean, −1 SD, and −2 SD of monthly cases in the previous 5 years, respectively. (B) Bar plots comparing monthly cases between 9 months (March through November) of 2020 (n = 9) and the corresponding 9 months of the previous 5 years (n = 45). P-values in the Mann–Whitney U test are indicated. SD, standard deviation.