The coronavirus responsible for COVID‑19, SARS‑CoV‑2, was first identified in late 2019 and quickly spread globally, bringing about a severe public health emergency of international concern. This review summarizes genetic evolution, mutation mechanisms, epidemiology trends and the impact of virus on vaccine induced immunity. With RNA replication error, recombination, and selective pressures, these have resulted in the emergence of several variants of concern such as Delta and Omicron with increased transmissibility with partial immune escape. The millions of new cases and hundreds of thousands of deaths are well documented in global and Iraqi epidemiological data; Iraq claims more than two million confirmed COVID cases. Viral mutations, most notably in the spike protein, have affected vaccine effectiveness, but booster doses and updated vaccines have helped protect against severe disease. Integrating genomic, epidemiological and immunological data is needed to inform ongoing public health responses, adapt the vaccine for evolving variants and ensure preparedness for other viral threats in the future.