Humoral and Cellular Immune Responses of COVID-19 vaccines against SARS-Cov-2 Omicron variant: a systemic review

Abstract

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has undergone multiple mutations since its emergence, and its latest variant, Omicron (B.1.1.529), is the most contagious variant of concern (VOC) which poses a major and imminent threat to public health. Since firstly reported by World Health Organization (WHO) in November 2021, Omicron variant has been spreading rapidly and has become the dominant variant in many countries worldwide. Omicron is the most mutated variant so far, containing 60 mutations in its genome, including 37 mutations in the S-protein. Since all current COVID-19 vaccines in use were developed based on ancestral SARS-CoV-2 strains, whether they are protective against Omicron is a critical question which has been the center of study currently. In this article, we systemically reviewed the studies regarding the effectiveness of 2-or 3-dose vaccines delivered in either homologous or heterologous manner. The humoral and cellular immune responses elicited by various vaccine regimens to protect against Omicron variant are discussed. Current understanding of the molecular basis underlying immune escape of Omicron was also analyzed. These studies indicate that two doses of vaccination are insufficient to elicit neutralizing antibody responses against Omicron variant. Nevertheless, Omicron-specific humoral immune responses can be enhanced by booster dose of almost all type vaccines in certain degree, and heterologous vaccination strategy may represent a better choice than homogenous regimens. Intriguingly, results of studies indicate that all current vaccines are still able to elicit robust T cell response against Omicron. Future focus should be the development of Omicron variant vaccine, which may induce potent humoral as well as cellular immune responses simultaneously against all known variants of the SARS-CoV-2 virus.

Reactogenicity and immunogenicity of the second COVID-19 vaccination in patients with inborn errors of immunity or mannan-binding lectin deficiency

“…Especially in light of the rapid mutation frequency of the SARS-CoV-2 virus, T cell response seems to be a key in generating a robust immune response ( 28 , 29 ). To investigate whether the IEI/MBLdef patients mounted a SARS-CoV-2 T cell specific response, we analyzed PBMCs from eleven patients in comparison to PBMCs of healthy controls.…”

The impact of sphingosine-1-phosphate receptor modulators on COVID-19 and SARS-CoV-2 vaccination

“…Importantly, this had biological impact because in comparison to other MS treatments, use of either fingolimod or CD20-depleting antibodies was sometimes associated with COVID-19 disease breakthrough following vaccination ( Schiavetti et al, 2022 , Garjani et al, 2022 , Bsteh et al, 2022 , Sormani et al, 2022 ). Importantly, this was seen even before the time when circulating SARS-CoV-2 variants of concern, notably omicron variants, required high vaccine-induced antibody titres to protect from infection compared to the initial SARS-CoV-2 variants ( Chen et al, 2022 , Sormani et al, 2022 , Cheng et al, 2022 , Tuekprakhon et al, 2022 ). As this breakthrough was associated with agents with poor seroconversion, it supports the view that viral neutralizing antibodies are particularly important in preventing infection/re-infection ( Baker et al, 2020a , Sormani et al, 2022 ).…”

“…With time, SARS-CoV-2 vaccines and anti-viral agents have been developed to fight the disease that has killed millions of people and created economic havoc ( Khoury et al, 2021 , Wu et al, 2022 , Gombolay et al, 2022 , Sendi et al, 2022 , Richards et al, 2022 ). However, this has created further challenges for use in immunosuppressed people ( Baker et al, 2020a ), especially as this is occurring within a landscape of global viral evolution and the generation of circulating SARS-CoV-2 variants that have different morbidities, contagion and immune-escape ( Chen et al, 2022 , Shrestha et al, 2022 ). However, as immune-escape is in part attributable to viral evolution in immunosuppressed individuals ( Weigang et al, 2021 , Scherer et al, 2022 ), it is important to optimise anti-viral therapy within the need to effectively control immune-mediated diseases.…”

Updated Insights into the T Cell-Mediated Immune Response against SARS-CoV-2: A Step towards Efficient and Reliable Vaccines

“…All these findings show that SARS-CoV-2-specific T-cell responses may retain protection against a number of variants, such as Delta and Omicron variants. Additionally, the T-cell-mediated response elicited by vaccines reduces the risk of severity and death in patients infected with SARS-CoV-2 despite the fact that all vaccines were generated using an ancestral virus [ 116 ]. This raises a very interesting question: do we actually need variant-specific vaccines?…”