New Delhi: The Covid-19 prevention protocols such as mask-wearing, hand-washing and physical distancing may have reduced the rate of Kawasaki disease in South Korea, a new study has found.
Kawasaki disease is the most common cause of heart disease that develops in children after birth, creating inflammation in blood vessels, particularly heart arteries. The cause of this disease is not well understood. It may be an immune response to an acute infectious illness.
It usually occurs before age 5 and is more common in India and other south Asian countries. South Korea has the second-highest incidence of Kawasaki disease in the world, after Japan.
For the study, published in the journal Circulation, the researchers looked at health records from January 2010 to September 2020 in a South Korean national health insurance database to identify Kawasaki disease cases among individuals from birth to 19 years.
They identified 53,424 cases of Kawasaki disease during the 10 years studied, and 83 per cent of cases occurred in children younger than 5 years of age.
Efforts to prevent Covid-19 provided a unique opportunity to analyse the possible effects of mask-wearing and social distancing on Kawasaki disease, the researchers said.
Since February 2020, South Korea has required strict mask-wearing, periodic school closures, physical distancing, and frequent testing and isolation for people with Covid-19 symptoms.
The team found that analysis found the number of Kawasaki cases dropped substantially — by about 40 per cent — after Covid-19 prevention efforts were implemented in February 2020.
Before 2020, the average number of cases of Kawasaki disease between February and September was 31.5 per 1 lakh people, compared to 18.8 per 1 lakh people for the same months in 2020 during the pandemic.
The greatest decrease in cases occurred among children up to age 9, while no decrease occurred among 10-19-year-olds.
Symptoms of Kawasaki disease include fever, rash, red and bumpy lips with enlarged taste buds. Prompt treatment is critical to prevent heart problems, and most children recover fully with treatment.
What the researchers found
“Our findings emphasize the possible impact of environmental triggers on the occurrence of Kawasaki disease,” Jong Gyun Ahn, associate professor of pediatrics Yonsei University College of Medicine in Seoul, South Korea, said in a statement.
“The decrease in the incidence of Kawasaki disease after the implementation of non-pharmaceutical interventions is very clear, and it is unlikely that other independent interventions were accidentally involved,” Ahn said.
“The broad and intensive COVID-19 prevention interventions had the additional effect of lowering the incidence of respiratory infections, which have previously been suggested as triggering agents for Kawasaki disease,” Ahn noted. “Additionally, the seasonality of the Kawasaki disease epidemic disappeared in South Korea. It is usually most prevalent in the winter, with a second peak in late spring-summer.”
Jane W. Newburger, an expert at the American Heart Association, who was not involved in the study, noted that the research findings are consistent with the hypothesis that Kawasaki disease is an immunologic reaction elicited in genetically susceptible people when exposed to viruses or other infectious agents in the environment.
“During the COVID pandemic, children were exposed to fewer viruses and other infectious agents. So the ‘natural experiment’ that occurred from isolation and masking of children supports the likelihood that Kawasaki disease is triggered by viruses or other infectious agents in the environment,” Newburger said.
According to the researchers, the rate of Kawasaki disease appears to have risen over the years worldwide. This could be due to improved awareness and recognition of the disease and more frequent diagnosis of incomplete Kawasaki disease and true increasing incidence.
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