Fig. 10.

Ranking the final outbreak size of countries under the free transmission of the novel variant. The immunity scale represents the proportion of the population in each country that gained cross-immune protection after the prior infection, and the final size is the proportion of the final infections resulting from the free transmission of the new variant in this country. The size of the bubbles denotes the relative size of the final size in each country. The ranking indicates the susceptibility of a country to a new variant, and from top to bottom indicates the ranking from lowest to highest, where the invasion of a new variant will cause the largest infection size in China while the smallest infection size in Denmark.