Cellular immune states in SARS-CoV-2-induced disease.

The general immune state plays important roles against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Cells of the immune system are encountering rapid changes during the acute phase of SARS-CoV-2-induced disease. Reduced fraction of functional CD8+ T cells, disrupted cross-talking between CD8+ T cells with dendritic cells (DCs), and impaired immunological T-cell memory, along with the higher presence of hyperactive neutrophils, high expansion of myeloid-derived suppressor cells (MDSCs) and non-classical monocytes, and attenuated cytotoxic capacity of natural killer (NK) cells, are all indicative of low efficient immunity against viral surge within the body. Immune state and responses from pro- or anti-inflammatory cells of the immune system to SARS-CoV-2 are discussed in this review. We also suggest some strategies to enhance the power of immune system against SARS-CoV-2-induced disease.

Mucosal delivery of nanovaccine strategy against COVID-19 and its variants.

Despite the global administration of approved COVID-19 vaccines (e.g., ChAdOx1 nCoV-19®, mRNA-1273®, BNT162b2®), the number of infections and fatalities continue to rise at an alarming rate because of the new variants such as Omicron and its subvariants. Including COVID-19 vaccines that are licensed for human use, most of the vaccines that are currently in clinical trials are administered via parenteral route. However, it has been proven that the parenteral vaccines do not induce localized immunity in the upper respiratory mucosal surface, and administration of the currently approved vaccines does not necessarily lead to sterilizing immunity. This further supports the necessity of a mucosal vaccine that blocks the main entrance route of COVID-19: nasal and oral mucosal surfaces. Understanding the mechanism of immune regulation of M cells and dendritic cells and targeting them can be another promising approach for the successful stimulation of the mucosal immune system. This paper reviews the basic mechanisms of the mucosal immunity elicited by mucosal vaccines and summarizes the practical aspects and challenges of nanotechnology-based vaccine platform development, as well as ligand hybrid nanoparticles as potentially effective target delivery agents for mucosal vaccines.

Development of novel vaccines using nanomaterials against COVID-19

The COVID-19 pandemic has severely impacted human lives. This massive disruptive outbreak of the SARS-Cov-2 virus rapidly became the cause of universal fatality on a large scale. History demonstrates that vaccination is the most effective approach to prevent or sustainably control diverse infectious diseases. This scenario demanded the global urgency to develop a successful vaccine to set human lives’ normalcy back. The global health-care community established a new paradigm of rapid vaccine development at unprecedented speed. In this regard, nanomaterials played a remarkable role in designing innovative vaccine platforms. In this chapter, we discuss promises and challenges associated with the deployment of nanomaterials for successful execution of vaccination programs that mainly comprise vaccine design, precise delivery, and administration. Vaccine efficacy largely depends on the strength of the defensive response generated by immune cells. Nanostructure materials favor vaccine customization by convenient tailoring to mimic natural targets of the host immune system. © 2022 Elsevier Inc. All rights reserved.