Comprehensive Review on COVID-19: Evolution, Diagnostics, Vaccines, Therapeutics and Societal Impact

The coronavirus disease 2019 (COVID-19) pandemic, produced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), signifies one of the most significant global health crises of the 21st century. Since its identification in late 2019, the virus has spread rapidly, resulting in profound clinical, societal, and economic consequences worldwide. Understanding the evolution of SARS-CoV-2, the emergence of variants of concern, and the ongoing development of diagnostics, vaccines, and therapeutics has been central to managing the pandemic. Diagnostic innovations ranging from RT-PCR and antigen testing to genomic sequencing have played a crucial role in outbreak control. Multiple vaccines, including mRNA-based, viral vector, and protein subunit platforms, have demonstrated strong protection, although waning immunity and viral mutations necessitate booster doses and updated formulations. Therapeutic options such as antivirals, monoclonal antibodies, and immunomodulators have significantly reduced morbidity and mortality, but challenges remain with resistance and variant-specific efficacy. Preventive measures, including masking, physical distancing, and vaccination campaigns, have mitigated spread, though inequitable distribution and vaccine hesitancy remain barriers. Beyond acute infection, long COVID and post-acute sequelae highlight the need for continued clinical monitoring and research. The pandemic has also reshaped economies, mental health, and environmental sustainability. This review synthesizes current evidence on SARS-CoV-2 biology, diagnostics, vaccines, therapeutics, and public health responses, while identifying knowledge gaps and priorities for future pandemic preparedness.