A Comparative Review of mRNA, ViralVector, Inactivated, and Protein SubunitCOVID-19 Vaccines

Abstract

The COVID-19 pandemic prompted an unprecedented global response in vaccine development. Multiple platforms, including mRNA, viral vector, inactivated, and protein subunit vaccines, were rapidly developed to curb the spread of SARS-CoV-2. This review provides a comparative analysis of these vaccine types, focusing on their mechanisms of action, efficacy, safety profiles, storage requirements, and global distribution. mRNA vaccines such as PfizerBioNTech and Moderna demonstrated high efficacy, while viral vector vaccines like AstraZeneca and Johnson & Johnson offered logistical advantages. Inactivated vaccines such as Covaxin and Sinopharm are based on traditional methods and showed good safety profiles. Protein subunit vaccines like Novavax are emerging as a promising alternative with minimal side effects. Understanding these differences is essential for informed public health decisions, vaccine acceptance, and future pandemic preparedness.