SARS-CoV-2 Variants, Vaccines, and Host Immunity

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new beta coronavirus that emerged at the end of 2019 in the Hubei province of China. SARS-CoV-2 causes coronavirus disease 2019 (COVID-19) and was declared a pandemic by the World Health Organization (WHO) on 11 March 2020. Herd or community immunity has been proposed as a strategy to protect the vulnerable, and can be established through immunity from past infection or vaccination. Whether SARS-CoV-2 infection results in the development of a reservoir of resilient memory cells is under investigation. Vaccines have been developed at an unprecedented rate and 7 408 870 760 vaccine doses have been administered worldwide. Recently emerged SARS-CoV-2 variants are more transmissible with a reduced sensitivity to immune mechanisms. This is due to the presence of amino acid substitutions in the spike protein, which confer a selective advantage. The emergence of variants therefore poses a risk for vaccine effectiveness and long-term immunity, and it is crucial therefore to determine the effectiveness of vaccines against currently circulating variants. Here we review both SARS-CoV-2-induced host immune activation and vaccine-induced immune responses, highlighting the responses of immune memory cells that are key indicators of host immunity. We further discuss how variants emerge and the currently circulating variants of concern (VOC), with particular focus on implications for vaccine effectiveness. Finally, we describe new antibody treatments and future vaccine approaches that will be important as we navigate through the COVID-19 pandemic.

Differential transcriptomic landscapes of multiple organs from SARS-CoV-2 early infected rhesus macaques

“…Following the discovery of SARS-CoV-2, the emergence of multiple variants has been reported, that are more transmissible with a reduced sensitivity to immune mechanisms (Karim and Karim, 2021 ; Mistry et al, 2021 ). Subsequently, fast-spreading variants displace local SARS-CoV-2 strain, and were classified as variants of concern (VOCs).…”

Significance of HLA Haplotypes in Two Patients with Subacute Thyroiditis Triggered by mRNA-Based COVID-19 Vaccine

“…Both also had a similar time lag between the vaccination and the onset of SAT symptoms (three weeks) and both had SAT triggered by the second dose of the same vaccine (BNT162b2-Pfizer-BioNTech), which obviously carried the same adjuvants. It remains unclear why the reaction was only after the second dose, although a mechanism related to immune memory and immunization with already known pathogens can be considered [31].…”

Omicron-specific mRNA vaccine elicits potent immune responses in mice, hamsters, and nonhuman primates

“…However, for those with disadvantages, such as old age, pre-existing conditions, or being vaccinated with less potent vaccines, Omicron still poses a considerable threat. A recent phase 4 clinical trial in Brazil indicates a significant fraction of people who received three doses still have Omicron neutralization titers lower or barely above the limit to be considered seropositive (Malik et al, 2022; Mistry et al, 2021). Thus, an Omicron effective vaccine is urgently needed.…”

“…A recent phase 4 clinical trial in Brazil indicates a significant fraction of people who received three doses still have Omicron neutralization titers lower or barely above the limit to be considered seropositive (Malik et al, 2022;Mistry et al, 2021). Thus, an Omicron effective vaccine is urgently needed.…”