Characteristics of Covid-19 infection with the original SARS-Cov-2 virus and other variants: A comparative review

The novel coronavirus infection (Covid-19) had enormous effects on global health. Since it first emerged (in China, three more clinically significant variants developed, which were differentiated from the original virus in terms of clinical course, hospitalization, mortality, and overall outcome. These variants are Alpha (British), Delta, and Omicron variants. Each variant was the prominent infectious variant of the Covid-19 virus for a specific time. While some variants were associated with higher mortality, others were associated with a higher spreading rate compared to the rest of the variants. The present review aimed to summarize the clinical characteristics, symptoms, need for hospitalization and intensive care, mortality, and overall outcomes of the original and other three significant variants of the Covid-19 infection. We also aimed to present a brief review of post covid syndrome.