Decline in Kawasaki disease may be linked to pandemic preventive measures
The decrease in Kawasaki disease rates in South Korea during the COVID-19 pandemic may be attributable to pandemic prevention efforts, including mask-wearing, hand-washing and physical distancing, researchers reported.
“In Korea, nonpharmaceutical interventions such as mandatory mask-wearing, school closure and testing and isolation of symptomatic individuals were implemented in February 2020, with good compliance,” Ji-Man Kang, MD, from the department of pediatrics at Severance Children’s Hospital and the Institute for Immunology and Immunological Diseases at Yonsei University College of Medicine, Seoul, South Korea, and colleagues wrote in Circulation. “This nationwide intervention provided a unique opportunity for us to investigate the collateral effect of nonpharmaceutical interventions on the incidence of other diseases.”
Researchers conducted a retrospective, ecologic study evaluating data from the National Health Insurance Service database on all 53,424 cases of Kawasaki disease among children aged 0 to 19 years from 2010 to September 2020. The nonpharmaceutical intervention period was defined as February to September 2020. Researchers compared the incidence rate of Kawasaki disease in the nonpharmaceutical intervention period with the annual mean incidence rate during the pre-nonpharmaceutical intervention period.
Of all cases, 83% occurred among children aged 5 years or younger and 17% were resistant to IV immunoglobulin. During the pre-nonpharmaceutical intervention period, annual mean Kawasaki disease incidence was 48.1 per 100,000 persons, with a monthly mean incidence of 4.1 per 100,000 persons. During the COVID-19 pandemic, Kawasaki disease incidence declined to less than 2 per 100,000 persons after nonpharmaceutical intervention implementation.
From February to September 2020, Kawasaki disease incidence in the nonpharmaceutical intervention period was 18.8 per 100,000 persons, which corresponded with 60% of the mean incidence in the pre-nonpharmaceutical intervention period and 58% of the predicted incidence (P = .085).
The highest Kawasaki disease incidence rate was among children aged 0 to 4 years at 80 per 100,000 persons, which was lower than the mean incidence of 123 per 100,000 persons during the pre-nonpharmaceutical intervention period (P = .003) and the predicted incidence of 123.3 per 100,000 persons. Among children aged 5 to 9 years, Kawasaki disease incidence was lower than the mean incidence in the pre-nonpharmaceutical intervention period (10.6 vs. 23.8 per 100,000 persons; P = .04) and the predicted incidence of 24.7 per 100,000 persons.
There was no difference in Kawasaki disease incidence before and after nonpharmaceutical intervention implementation among those aged 10 to 19 years.
According to a press release, these results may have been possible due to Kawasaki disease being an immunologic reaction in genetically susceptible individuals when exposed to viruses and other infectious agents.
“This nationwide study reveals that the Kawasaki disease incidence decreased significantly after the implementation of nonpharmaceutical interventions in Korea,” the researchers wrote. “Further long-term research is needed to determine whether the decrease in incidence of Kawasaki disease is solely attributable to the effects of nonpharmaceutical interventions.”