The journey so far with SARS-CoV-2 variants: Pathogenesis, immunity and treatments

Abstract

The recruitment of therapeutics and most importantly COVID-19 vaccines has seen a measurable reduction in transmission, re-infection, severity, hospitalization and mortality associated with the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The development and approval of some vaccines and therapeutics undoubtedly signaled renewed hope for public health personnel, the government, the World Health Organization (WHO) and the entire world population. At present, most countries have progressed beyond administering first and second doses to administering COVID-19 vaccine updated boosters to prevent transmission and provide protection. Notably, a bivalent COVID-19 vaccine from Pfizer–BioNTech and Moderna, also called an “updated” COVID-19 vaccine booster dose, is a formulation that houses the original virus strain and omicron BA.1, which provides broad immunity against COVID-19 including the omicron variant (BA.1) and the Paxlovid drug (Nirmatrelvir-ritonavir) authorized for use by the Food and Drug Administration (FDA) and the European Medicines Agency. This current review outlines the variant of concern (VOC), viral cell entry and pathogenesis, host immunity and viral immune evasion. In addition, we discuss the therapeutic and vaccine treatment approach, WHO and FDA authorization, vaccine storage and vaccine efficacy. In conclusion, bearing in mind the trend of continued mutations as observed on the spike (S) glycoprotein and receptor binding domain (RBD) of SARS-CoV-2, which lead to more immune-evasive strains such as BQ.1, BQ.1.1, BF.7, XBB and XBB.1, researcher and clinician attention should be tailored toward the design and development of variant-specific vaccines for future interventions.