From:  Advancements in viral vaccine development: from traditional to modern approaches

 Differences between subunit, protein-based, reverse vaccinology, and messenger RNA (m-RNA)-based vaccines

Vaccine typeMechanismAdvantagesLimitationsExamplesReference
Subunit vaccinesUse isolated components (e.g., proteins, polysaccharides)Safe; no live pathogensLower immunogenicity; often requires adjuvants; challenging to produce epitopes for all strainsHepatitis B [recombinant hepatitis B surface antigen (HBsAg)], human papillomavirus (HPV) (Gardasil®)[44]
Protein-based vaccinesUtilize pathogen-specific proteins (often purified or recombinant)Highly specific; can be combined with adjuvants; stableLimited efficacy against pathogens with rapid mutationNovavax COVID-19 vaccine (protein subunit)[45]
Reverse vaccinologyUses genomic sequencing to identify antigenic targetsEnables vaccine development for difficult pathogens; faster discoveryComputational predictions may not always yield effective antigensMulti-epitope-based peptide vaccine against avian rotavirus (AvRV) strains[47]
m-RNA vaccinesDeliver m-RNA encoding viral or pathogen-derived proteinsRapid development; no need for live pathogens; strong cellular/humoral immunityRequires cold chain storage; risk of instabilityPfizer-BioNTech and Moderna COVID-19 vaccines[46]