effectiveness of coronavirus vaccines against syndrome coronavirus 2 (sars-cov-2) and its new variants

The widespread outbreak of coronavirus disease 2019 in late 2019 caused many people worldwide to die or suffer from certain clinical complications even after the recovery. the virus has many social and economic adverse effects. studies on severe acute respiratory syndrome coronavirus 2 (sars-cov-2) have specified that spike, surface glycoprotein antigen, is considered as a major target to stimulate the immune system. this glycoprotein binds to the angiotensin-converting enzyme 2 on the surface of human cells especially lung epithelial cells and facilitates the virus entry. therefore, the immune response stimulated by vaccination targeting this antigen may cause immunity against the whole virus. currently, many companies are working on sars-cov-2 vaccines. they include ‘traditional’ vaccines like attenuated or inactivated virus platforms as well as the brand-new generations of vaccines such as viral vector-based, subunit, nucleic acid-based, and virus-like particle vaccines. certainly, each vaccine platform presents several advantages and disadvantages affecting its efficacy and safety which is the main topic of this paper.