Pandemics end when the pathogen causing them runs out of individuals to infect. Some of those susceptible will have died. Enough of the rest would then be immune for the population to have developed “herd immunity”. In the case of the current pandemic of sars-cov-2, the more silent infections there have been, the faster this herd immunity will arrive. 当疫情结束时，病原体将会消耗完易感染的个体。这些人中抵抗能力较差的将会死亡。剩下的人都具备足够的免疫力，会形成“免疫群体”。目前新冠病毒肆虐的情况下，越多的无症状感染，免疫群体将会越快形成。
ferocity 凶残猛烈
draw on 利用
asymptomatic 无症状的
unwitting 不知情的，糊涂的