Immune Responses to SARS CoV-2: A Scoping Review

Abstract

COVID-19 is noxious and constitutes a raft of adverse multiplier effects. As such, there is urgent need to understand the disease well and take action to mitigate its punitive pathologic & economic outcomes. Comprehending the conduct of the immune system during and after infection may provide fundamental leads to unraveling effective interventions. Some vaccines and drugs have since been validated and made available for emergency use among priority populations. However, these vaccines were developed at an accelerated pace and mainly on the basis of rudimentary immunological & molecular events. Therefore, there is need for continuous revelation of precise and more elaborate hallmarks in order to improve on, or develop more efficacious and safe interventions. Three scientific databases (PubMed, Cochrane and EMBASE) were searched between 1st December, 2020 and 15th January, 2021 for information about immune responses to SARS COV-2. Studies that utilized experimental designs, exhibited little to no likelihood of bias, published in highly refereed and peer reviewed journals were selected. A total of 10 papers were shortlisted for the final synthesis. A set of cytokines including: IL-2, IL-6, IL-7, IL-10, TNF, and GM-CSF are recovered in most cases. However, IL-6 is featured in most severe and fatal events. There wasn’t congruency by different studies on the precise conduct of T-cells during infection. Some studies reported elevated levels of both CD+4 & CD+8 T-cells among severe cases while others reported exhausted elevated levels of the same immunological parameters during mild disease. Higher levels of Natural Killer-cells (NK-cells) as well as Neutralizing Antibodies (Nabs) correlate with better disease outcomes. However, considering the role played by Abs in the production of cytokines (pro and anti-inflammatory), it may be crucial to profile the risk/benefit ratio of Abs during infection. Interventions that seek to: reverse high production of pro-inflammatory cytokines (IL-6), potentiate release and function of NK-cells, as well as Nabs and moderate exhaustion of CD+4 & CD+8 T-cells, may constitute promising outcomes.