Background: Since the emergence of SARS-CoV-2 in Wuhan, China, numerous Variants of Concern (VOC) have surfaced, each presenting unique challenges to mitigating disease transmission. These variants have varying degrees of transmissibility, pathogenicity, symptoms, and disease severity. Dealing with these variants has posed new challenges in controlling the spread of the virus.

Objective: We compiled current and prior evidence of VOCs with the goal to study the timeline, prevalence, pathogenesis, transmission, symptoms, and disease severity of SARS-CoV-2 variants, as well as the therapeutic management and vaccine efficacy against each respective VOC.

Methods: Five criteria for review were established for each variant including timeline, pathogenesis, transmission, severity of disease, and treatment. PubMed, BioRxiv, and other databases were searched for articles regarding VOC and original lineage strains, while information regarding other variants was excluded. The search was conducted from October 2019 to October 2021. Articles regarding original lineage strains and VOC or VOI were included while information regarding other variant classifications were excluded. Compiled information was organized chronologically to evaluate the timeline of SARS-CoV-2 strains.

Results: This paper follows the SARS-CoV-2 parent strain from its origin in Wuhan, China and the mutations which caused prevalent variants throughout the globe. With each mutation, VOCs were found to have unique substitutions which largely caused more efficient spike protein binding to the host receptor and more efficient evasion of the host immune response.

Conclusion: SARS-CoV-2 VOCs are strongly associated with increased transmission and severity of the virus, underscoring the importance of vaccination in controlling the pandemic.