Heterogeneity and herd immunity In response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), some politicians have been keen to exploit the idea of achieving herd immunity. Countering this possibility are estimates derived from work on historical vaccination studies, which suggest that herd immunity may only be achieved at an unacceptable cost of lives. Because human populations are far from homogeneous, Britton et al. show that by introducing age and activity heterogeneities into population models for SARS-CoV-2, herd immunity can be achieved at a population-wide infection rate of ∼40%, considerably lower than previous estimates. This shift is because transmission and immunity are concentrated among the most active members of a population, who are often younger and less vulnerable. If nonpharmaceutical interventions are very strict, no herd immunity is achieved, and infections will then resurge if they are eased too quickly. Science, this issue p. 846 Human population heterogeneities bring down estimates for herd immunity. Despite various levels of preventive measures, in 2020, many countries have suffered severely from the coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus. Using a model, we show that population heterogeneity can affect disease-induced immunity considerably because the proportion of infected individuals in groups with the highest contact rates is greater than that in groups with low contact rates. We estimate that if R0 = 2.5 in an age-structured community with mixing rates fitted to social activity, then the disease-induced herd immunity level can be ~43%, which is substantially less than the classical herd immunity level of 60% obtained through homogeneous immunization of the population. Our estimates should be interpreted as an illustration of how population heterogeneity affects herd immunity rather than as an exact value or even a best estimate.

中文翻译：

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数学模型揭示了群体异质性对 SARS-CoV-2 群体免疫的影响


异质性和群体免疫为了应对严重急性呼吸综合征冠状病毒 2 (SARS-CoV-2)，一些政治家一直热衷于利用实现群体免疫的想法。与这种可能性相反的是，历史疫苗研究工作得出的估计表明，群体免疫可能只有以不可接受的生命代价才能实现。由于人类群体远非同质，布里顿等人。研究表明，通过将年龄和活动异质性引入 SARS-CoV-2 人群模型中，可以在全人群感染率约为 40% 的情况下实现群体免疫，远低于之前的估计。这种转变是因为传播和免疫力集中在人群中最活跃的成员中，他们通常更年轻且不易受到伤害。如果非药物干预措施非常严格，就无法实现群体免疫，如果放松得太快，感染就会死灰复燃。科学，本期第 14 页。 846 人口异质性降低了群体免疫力的估计值。尽管采取了不同程度的预防措施，2020年，许多国家仍然遭受了由严重急性呼吸综合征冠状病毒2（SARS-CoV-2）病毒引起的2019冠状病毒病（COVID-19）大流行的严重影响。使用模型，我们表明群体异质性可以显着影响疾病引起的免疫力，因为接触率最高的群体中感染个体的比例大于接触率低的群体中的感染个体的比例。我们估计如果 R0 = 2。5 在年龄结构的社区中，混合率与社会活动相适应，那么疾病引起的群体免疫水平可达 43% 左右，这大大低于通过人群同质免疫获得的经典群体免疫水平 60%。我们的估计应该被解释为群体异质性如何影响群体免疫的说明，而不是一个精确值，甚至是最佳估计。