https://www.mhlw.go.jp/content/10900000/001067304.pdfhttps://www.england.nhs.uk/long-read/preparing-for-a-successful-spring-2023-covid-19-booster-campaign/https://www.bag.admin.ch/bag/en/home/krankheiten/ausbrueche-epidemien-pandemien/aktuelle-ausbrueche-epidemien/novel-cov/impfen.htmlhttps://www.rivm.nl/en/covid-19-vaccination/questions-and-background-information/repeat-vaccination
http://www.nicovideo.jp/watch/sm42062050
