1 Download historical data (to 14 December 2020) on the daily number of new reported COVID-19 cases and deaths worldwide [Internet]. Solna (Sweden): European Centre for Disease Prevention and Control (European Union) [cited 2020 Dec 28]. Available from: https://www.ecdc.europa.eu/ en/publications-data/download-todays-data-geographic- distribution-covid-19-cases-worldwide.
2 Coronavirus: The world in lockdown in maps and charts [Internet]. London: BBC News [cited 2020 April 7]. Available form: https://www.bbc.com/news/world-52103747.
3 Reddy RK, Charles WN, Sklavounos A, Dutt A, Seed PT, Khajuria A. The effect of smoking on COVID-19 sever- ity: a systematic review and meta-analysis. J Med Virol. 2021;93:1045-56. DOI: 10.1002/jmv.26389, PMID: 32749705
4 Tsigaris P, Teixeira da Silva JA. Smoking prevalence and COVID-19 in Europe. Nicotine Tob Res. 2020;22:1646-9. DOI: 10.1093/ntr/ntaa121, PMID: 32609839
5 Miyasaka M. Is BCG vaccination causally related to reduced COVID‐19 mortality? EMBO Mol Med. 2020;12:e12661. DOI: 10.15252/emmm.202012661, PMID: 32379923
6 Ebina-Shibuya R, Horita N, Namkoong H, Kaneko T. National policies for paediatric universal BCG vaccination were associated with decreased mortality due to COVID ‐19. Respirology. 2020;25:898-9. DOI: 10.1111/resp.13885, PMID: 32558034
7 Escobar LE, Molina-Cruz A, Barillas-Mury C. BCG vaccine protection from severe coronavirus disease 2019 (COVID-19). Proc Natl Acad Sci USA. 2020;117:17720-6. DOI: 10.1073/ pnas.2008410117, PMID: 32647056
8 Hamiel U, Kozer E, Youngster I. SARS-CoV-2 Rates in BCG-vaccinated and unvaccinated young adults. JAMA. 2020;323:2340-1. DOI: 10.1001/jama.2020.8189, PMID: 32401274
9 Wassenaar TM, Buzard GS, Newman DJ. BCG vaccination early in life does not improve COVID‐19 outcome of elderly populations, based on nationally reported data. Lett Appl Microbiol. 2020;71:498-505. DOI: 10.1111/lam.13365, PMID: 32734625
10 Licciardi F, Pruccoli G, Denina M, Parodi E, Taglietto M, Rosati S, et al. SARS-CoV-2–Induced Kawasaki-Like Hyperinflammatory Syndrome: A Novel COVID Phenotype in Children. Pediatrics. 2020;146:e20201711. DOI: 10.1542/ peds.2020-1711, PMID: 32439816
11 Doorslaer E, Koolman X, Jones AM. Explaining income- related inequalities in doctor utilisation in Europe. Health Econ. 2004;13:629-47. DOI: 10.1002/hec.919, PMID: 15259043
12 Gaia C, Maria Chiara C, Silvia L, Chiara A, Maria Luisa DC, Giulia B, et al. Chest CT for early detection and management of coronavirus disease (COVID-19): a report of 314 patients admitted to Emergency Department with suspected pneu- monia. Radiol Med (Torino). 2020;125:931-42. DOI: 10.1007/ s11547-020-01256-1, PMID: 32729028
13 Status of positive test cases in each prefecture (Domestic cases excluding airport quarantine and charter flights) [Inter- net]. Tokyo: Ministry of Health, Labour and Welfare, Japan [cited 2020 Sep 7]. Available from: https://www.mhlw.go.jp/ content/10906000/000663402.pdf. Japanese.
14 OECD Statistics [Internet]. Paris: Organization for Economic Co-operation and Development [cited 2020 Sep 20]. Available from: https://stats.oecd.org/.
15 Baloch S, Baloch MA, Zheng T, Pei X. The coronavirus disease 2019 (COVID-19) pandemic. Tohoku J Exp Med. 2020;250:271-8. DOI: 10.1620/tjem.250.271, PMID: 32321874
16 Dudley JP, Lee NT. Disparities in age-specific morbidity and mortality from SARS-CoV-2 in China and the Republic of Korea. Clin Infect Dis. 2020;71:863-5. DOI: 10.1093/cid/ ciaa354, PMID: 32232322
17 Goldstein JR, Lee RD. Demographic perspectives on the mortality of COVID-19 and other epidemics. Proc Natl Acad Sci USA. 2020;117:22035-41. DOI: 10.1073/pnas.2006392117, PMID: 32820077
18 Urban population (% of total population) [Internet]. Wash- ington, D.C.: The World Bank [cited 2020 Sep 7]. Available from: https://data.worldbank.org/indicator/SP.URB.TOTL. IN.ZS.
19 Age dependency ratio, old (% of working-age population) [Internet]. Washington, D.C.: The World Bank [cited 2020 Sep 7]. Available from https://data.worldbank.org/indicator/ SP.POP.DPND.OL.
20 Primary Health Care on the Road to Universal Health Cover- age 2019 Monitoring report [Internet]. Geneva: World Health Organization [cited 2020 Sep 7]. Available from: https://www. who.int/docs/default-source/documents/2019-uhc-report.pdf.
21 BCG Immunization coverage estimates by country [Internet]. Geneva: World Health Organization [cited 2020 Sep 7]. Available from: https://apps.who.int/gho/data/view. main.80500?lang=en.
22 Lin MT, Wu MH. The global epidemiology of Kawasaki dis- ease: review and future perspectives. Glob Cardiol Sci Pract. 2017;2017:e201720. DOI: 10.21542/gcsp.2017.20, PMID: 29564341
23 Kim GB. Reality of Kawasaki disease epidemiology. Korean J Pediatr. 2019;62:292-6. DOI: 10.3345/kjp.2019.00157, PMID: 31319643
24 Oxford COVID-19 Government Response Tracker, Blavatnik School of Government. Data use policy: Creative Commons 2020 [Internet]. Hale, Thomas, Angrist N, Cameron-Blake E, Hallas L, Kira B, et al. [cited 2020 Sep 7]. Available from: https://covidtracker.bsg.ox.ac.uk/stringency-scatter.
25 Population estimates 2019. April 14, 2020 [Internet]. Tokyo: Statistics Bureau of Japan [cited 2020 July 30]. Available from: https://www.stat.go.jp/data/jinsui/2019np/index.html. Japanese.
26 Statistical reports on the land area by prefectures and munici- palities in Japan. Dec 26,2019 [Internet]. Tsukuba: Geospatial Information Authority of Japan [cited 2020 Sep 7]. Available from: https://www.gsi.go.jp/KOKUJYOHO/MENCHO/ backnumber/GSI-menseki20191001.pdf. Japanese.
27 Population of densely inhabited district by prefecture, 2015 [Internet]. Tokyo: National Institute of Population and Social Security Research [cited 2020 Sep 7]. Available from: http:// www.ipss.go.jp/syoushika/tohkei/Popular/P_Detail2020. asp?fname=T12-22.htm&title1=%87%5D%87U%81D%93 s%93%B9%95%7B%8C%A7%95%CA%93%9D%8Cv&t itle2=%95%5C12%81%7C22+%93s%93%B9%95%7B%8. Japanese.
28 Survey of Physicians, Dentists and Pharmacists 2018 [Inter- net]. Tokyo: Ministry of Health, Labour and Welfare, Japan [cited 2020 Sep 7]. Available from: https://www.mhlw.go.jp/ toukei/saikin/hw/ishi/18/index.html. Japanese.
29 Static/Dynamic Survey of Medical Institutions and Hospital Report 2017, Dec 27, 2018 [Internet]. Tokyo: Ministry of Health, Labour and Welfare, Japan [cited 2020 Seo 7]. Available from: https://www.mhlw.go.jp/toukei/saikin/hw/ iryosd/17/dl/09gaikyo29.pdf. Japanese.
30 Cancer Information Service, National Cancer Center, Japan. Smoking rate by prefecture from Comprehensive Survey of Living Conditions 2019, Ministry of Health, Labour and Welfare, Japan [Internet]. Cancer Registry and Statistics [cited 2019 Sep 7]. Available from: https://ganjoho.jp/data/reg_stat/ statistics/dl/Pref_Smoking_Rate(2001_2019).xls. Japanese.
31 Japan Tourism Statistics. The number of guests staying at accommodations in each prefecture of Japan by country/area, 2018, Aug 5, 2020 [Internet]. Tokyo: Japan National Tourism Organization [cited 2020 Sep 7]. Available from: https:// statistics.jnto.go.jp/en/graph/#graph--inbound--prefecture--ranking.
32 Abedi V, Olulana O, Avula V, Chaudhary D, Khan A, Shahjouei S, et al. Racial, Economic, and Health Inequality and COVID-19 Infection in the United States. J Racial Ethn Health Disparities. 2020;1:1-11. DOI: 10.1007/s40615-020- 00833-4, PMID: 32875535
33 News about Kawasaki disease and COVID-19 [Internet]. Tokyo: Japanese Society of Kawasaki Disease [cited 2020 Sep 7]. Available from: http://www.jskd.jp/pdf/20200508COVID- 19andKD.pdf. Japanese.
34 Mahajan UV, Larkins-Pettigrew M. Racial demographics and COVID-19 confirmed cases and deaths: a correlational analy- sis of 2886 US counties. J Public Health (Oxf). 2020;42:445-7. DOI: 10.1093/pubmed/fdaa070, PMID: 32435809
35 Goldstein JR, Atherwood S. Improved measurement of racial/ethnic disparities in COVID-19 mortality in the United States. medRxiv 2020;2020.05.21.20109116. DOI: 10.1101/2020.05.21.20109116.
36 Watanabe S, Wahlqvist ML. Covid-19 and dietary socioecol- ogy: risk minimisation. Asia Pac J Clin Nutr. 2020;29:207-19. DOI: 10.6133/apjcn.202007_29(2).0001, PMID: 32674226
37 Nakamura Y. [Etiology and pathogenesis of Kawasaki dis- ease]. Nihon Rinsho. 2016;74(suppl 6):503-7. PMID: 30547547 Japanese.
38 The National Survey on the Natural Environment. Report of the distributional survey of Japanese animals (Birds). 2004 [Internet]. Fujiyoshida: Biodiversity center of Japan [cited 2020 Sep 7]. Available from: http://www.biodic.go.jp/ reports2/6th/6_bird/6_bird.pdf. Japanese.