Will vaccine-derived protective immunity curtail COVID-19 variants in the US?
Will vaccine-derived protective immunity curtail COVID-19 variants in the US?
复制标题
DOI：
10.1016/j.idm.2021.08.008
复制
发表时间：
2021
影响因子：
8.8
通讯作者：
Gumel AB
中科院分区：
文献类型：
--
作者：
Mancuso M;Eikenberry SE;Gumel AB
目前多种有效的疫苗正在被用于抗击新冠疫情，并且在疫苗接种率中等到较高的地区，这些疫苗被视为显著降低疾病负担的主要因素。然而，新冠疫苗接种计划的有效性受到新型新冠病毒变异株出现的严重威胁，这些变异株除了比野生型（原始）毒株更具传染性外，还可能至少部分逃避现有疫苗的作用。设计了一个双毒株（一种野生型，一种变异株）和两组（接种疫苗组和未接种疫苗组）的机制数学模型，并用于评估疫苗诱导的交叉保护效力对美国新冠疫情传播的影响。对该模型的严谨分析表明，在没有任何同时传播的新冠病毒变异株的情况下，如果59%的美国人口完全接种辉瑞或莫德纳疫苗，就可以达到消除野生型毒株所需的疫苗衍生群体免疫阈值。如果野生型毒株与阿尔法变异株（一种比野生型毒株传染性高56%的新冠病毒变异株）同时传播，这个阈值会提高到76%。如果野生型毒株与德尔塔变异株（据估计比野生型毒株传染性高100%）同时传播，多达82%的美国人口需要接种上述任何一种疫苗才能实现疫苗衍生的群体免疫。对该模型的全局敏感性分析揭示了以下四个参数对驱动美国变异株的再生数（因此也是新冠疫情动态）的值最具影响力：(a)同时传播的新冠病毒变异株的传染性，(b)针对野生型毒株完全接种（使用辉瑞或莫德纳疫苗）的个体比例，(c)疫苗对变异株提供的交叉保护效力，以及(d)考虑到发生突破性感染的完全接种个体传染性降低的修正参数。具体而言，该模型的数值模拟表明，如果这两种疫苗对变异株提供中等水平的交叉保护（至少67%），美国就可以防止新冠疫情未来的波峰或激增。这项研究进一步表明，如果(i)针对野生型毒株的疫苗覆盖率较低（大致<66%），(ii)变异株比野生型毒株传染性强得多（例如，传染性高100%），或者(iii)疫苗提供的交叉保护水平相对较低（例如，低于50%），一种新的新冠病毒变异株可能会在美国导致疾病大幅激增。如果一种新的新冠病毒变异株只是比野生型毒株传染性略高（例如，阿尔法变异株，比野生型毒株传染性高56%），至少66%的美国人口完全接种疫苗，并且在美国使用的三种疫苗（辉瑞、莫德纳和强生）对变异株提供中等水平的交叉保护，那么这种变异株不会在美国导致这样的激增。
Multiple effective vaccines are currently being deployed to combat the COVID-19 pandemic, and are viewed as the major factor in marked reductions of disease burden in regions with moderate to high vaccination coverage. The effectiveness of COVID-19 vaccination programs is, however, significantly threatened by the emergence of new SARS-COV-2 variants that, in addition to being more transmissible than the wild-type (original) strain, may at least partially evade existing vaccines. A two-strain (one wild-type, one variant) and two-group (vaccinated or otherwise) mechanistic mathematical model is designed and used to assess the impact of the vaccine-induced cross-protective efficacy on the spread the COVID-19 pandemic in the United States. Rigorous analysis of the model shows that, in the absence of any co-circulating SARS-CoV-2 variant, the vaccine-derived herd immunity threshold needed to eliminate the wild-type strain can be achieved if 59% of the US population is fully-vaccinated with either the Pfizer or Moderna vaccine. This threshold increases to 76% if the wild-type strain is co-circulating with the Alpha variant (a SARS-CoV-2 variant that is 56% more transmissible than the wild-type strain). If the wild-type strain is co-circulating with the Delta variant (which is estimated to be 100% more transmissible than the wild-type strain), up to 82% of the US population needs to be vaccinated with either of the aforementioned vaccines to achieve the vaccine-derived herd immunity. Global sensitivity analysis of the model reveal the following four parameters as the most influential in driving the value of the reproduction number of the variant strain (hence, COVID-19 dynamics) in the US: (a) the infectiousness of the co-circulating SARS-CoV-2 variant, (b) the proportion of individuals fully vaccinated (using Pfizer or Moderna vaccine) against the wild-type strain, (c) the cross-protective efficacy the vaccines offer against the variant strain and (d) the modification parameter accounting for the reduced infectiousness of fully-vaccinated individuals experiencing breakthrough infection. Specifically, numerical simulations of the model show that future waves or surges of the COVID-19 pandemic can be prevented in the US if the two vaccines offer moderate level of cross-protection against the variant (at least 67%). This study further suggests that a new SARS-CoV-2 variant can cause a significant disease surge in the US if (i) the vaccine coverage against the wild-type strain is low (roughly <66%) (ii) the variant is much more transmissible (e.g., 100% more transmissible), than the wild-type strain, or (iii) the level of cross-protection offered by the vaccine is relatively low (e.g., less than 50%). A new SARS-CoV-2 variant will not cause such surge in the US if it is only moderately more transmissible (e.g., the Alpha variant, which is 56% more transmissible) than the wild-type strain, at least 66% of the population of the US is fully vaccinated, and the three vaccines being deployed in the US (Pfizer, Moderna, and Johnson & Johnson) offer a moderate level of cross-protection against the variant.
影响因子：
7.8
作者：
Betti M;Bragazzi N;Heffernan J;Kong J;Raad A
通讯作者：
Raad A
影响因子：
5.5
作者：
ANDERSON, RM
通讯作者：
ANDERSON, RM
影响因子：
2
作者：
BLOWER, SM;DOWLATABADI, H
通讯作者：
DOWLATABADI, H