Map of the location and situation of four municipalities in China and Hubei Province in which the pandemic initially occurred.

Source of original data on resident population and area size of regions: Bulletin of the 7th National Population Census (NPC) of China; https://www.gov.cn/guoqing/2021-05/13/content_5606149.htm, and Statistical Tables of Administrative Divisions of the People’s Republic of China; https://xzqh.mca.gov.cn/statistics/2022.html.