Immune response to SARS-CoV-2 variants: A focus on severity, susceptibility, and preexisting immunity

The heterogeneous phenotypes among patients with coronavirus disease 2019 (COVID-19) has drawn worldwide attention, especially those with severe symptoms without comorbid conditions. Immune responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative virus of COVID-19, occur mainly by the innate immune response via the interferon (IFN)-mediated pathways, and the adaptive immunity via the T lymphocyte and the antibody mediated pathways. The ability of the original Wuhan SARS-CoV-2 strain, and possibly more so with new emerging variants, to antagonize IFN-mediated antiviral responses can be behind the higher early viral load, higher transmissibility, and milder symptoms compared to SARS-CoV and are part of the continued clinical evolution of COVID-19. Since it first emerged, several variants of SARS-CoV-2 have been circulating worldwide. Variants that have the potential to elude natural or vaccine-mediated immunity are variants of concern. This review focuses on the main host factors that may explain the immune responses to SARS-CoV-2 and its variants in the context of susceptibility, severity, and preexisting immunity.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of King Saud Bin Abdulaziz University for Health Sciences. CC_BY_NC_ND_4.0

Automated summary

This article discusses the heterogeneous phenotypes among COVID-19 patients and the impact of SARS-CoV-2 and its variants on immune responses. The article points out that the ability of the SARS-CoV-2 strain and new emerging variants to antagonize IFN-mediated antiviral responses can lead to higher early viral load, higher transmissibility, and milder symptoms. Among the circulating variants of SARS-CoV-2, there are some variants of concern that have the potential to evade immune responses.