- Four major vaccine types are nearly ready: mRNA, viral vector, protein subunit, and inactivated/attenuated virus.
- mRNA vaccines (BioNTech/Pfizer, Moderna) use modified mRNA to evade immune response and stabilize the spike protein.
- CureVac's CVnCoV uses unmodified mRNA, acting as an adjuvant but with lower protein expression.
- Viral vector vaccines (Oxford/AstraZeneca, Janssen, Sputnik V) use modified adenoviruses to deliver spike protein instructions.
- Oxford/AstraZeneca uses an unmodified spike protein, while others incorporate proline substitutions for stability.
- Protein subunit vaccine (Novavax) directly injects a stabilized spike protein with an adjuvant (Matrix-M).
- Spike protein modifications (2P) lock the pre-fusion conformation, improving immune response against the virus.
- Modified mRNA increases stability and reduces innate immune activation; unmodified mRNA can enhance adjuvant effects.
- Viral vector vaccines offer advantages like stability at room temperature and easier production.