Cell
Volume 184, Issue 26, 22 December 2021, Pages 6229-6242.e18
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Article
Population impact of SARS-CoV-2 variants with enhanced transmissibility and/or partial immune escape

https://doi.org/10.1016/j.cell.2021.11.026Get rights and content
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open access

Highlights

  • Modeled impacts of different SARS-CoV-2 variants across range of scenarios

  • Enhanced transmissibility leads to more infections and narrows margin for control

  • Partial immune escape often remains rare and may not limit vaccination impact

  • Impact of immune escape is much greater when paired with enhanced transmissibility

Summary

SARS-CoV-2 variants of concern exhibit varying degrees of transmissibility and, in some cases, escape from acquired immunity. Much effort has been devoted to measuring these phenotypes, but understanding their impact on the course of the pandemic—especially that of immune escape—has remained a challenge. Here, we use a mathematical model to simulate the dynamics of wild-type and variant strains of SARS-CoV-2 in the context of vaccine rollout and nonpharmaceutical interventions. We show that variants with enhanced transmissibility frequently increase epidemic severity, whereas those with partial immune escape either fail to spread widely or primarily cause reinfections and breakthrough infections. However, when these phenotypes are combined, a variant can continue spreading even as immunity builds up in the population, limiting the impact of vaccination and exacerbating the epidemic. These findings help explain the trajectories of past and present SARS-CoV-2 variants and may inform variant assessment and response in the future.

Keywords

SARS-CoV-2
COVID-19
variant of concern
VOC
transmissibility
immune escape
vaccination
nonpharmaceutical interventions
NPI
mathematical model

Data and code availability

  • This study did not use or generate data aside from the reproducible output of the mathematical model.

  • All original code, including that needed to generate the figures in the main text and supplemental information, has been deposited in Open Science Framework and is publicly available as of the date of publication. The digital object identifier (DOI) is listed in the key resources table.

  • Any additional information required to use or analyze the model described in this paper is available from the lead contact upon request.

Cited by (0)

2

These authors contributed equally

3

Lead contact