No relationship was observed between Kawasaki disease and COVID-19 in Japan.

During the time of the COVID‐19 pandemic, there have been reports on the relationship between Kawasaki disease (KD) and SARS‐Cov‐2 from the United States, Europe, and other parts of the world. , However, there have been no such reports from Japan, until now. Japan has the largest number of KD patients in the world. Besides a nationwide survey of KD, Japan also has a national surveillance system of the disease. , Under this system, 199 participating hospitals promptly register all patients who have been diagnosed with KD by a pediatrician.

On July 13 2020, all the participating hospitals were asked to report the number of KD patients with a polymerase chain reaction (PCR) test and the number of positive PCR cases among them.

Of the 199 hospitals, 50 responded by July 21. A total of 496 KD patients were registered by the 50 hospitals between January 1 and July 21 2020. Of the 496 patients, PCR was conducted for 81 patients, including six patients with both a PCR and an antigen test. In addition, an antigen test was conducted for 12 patients and a loop‐mediated isothermal amplification test was administered to another five patients. None of the 98 patients tested presented a positive result for SARS‐Cov‐2. For the other 412 KD patients, the pediatricians treating them did not consider it necessary to conduct a test for the virus because of the patients’ symptoms, laboratory data, and other relevant information. In other words, patients with KD who did not present the COVID‐19 symptoms were not tested with PCR; however, this may be a limitation of this observation.

Finally, the situation regarding Covid‐19 infection in Japan, according to the Ministry of Health, Labour and Welfare, as of August 19 2020 is presented.

In conclusion, according to our observation, no KD patients showed a relationship with COVID‐19 in Japan. Among 57 140 patients with COVID‐19, there were 1,144 (2.0%) patients who were younger than 10 years, with no severe nor fatal cases (https://www.mhlw.go.jp/content/10906000/000661165.pdf).

According to our observation, no KD patients showed a relationship with COVID‐19 in Japan.

Funding

This study received funding from the Japan Kawasaki Disease Research Center, a non‐profit organization.

Disclosure

The author declares no conflict of interest.