A lyophilised formulation of chimpanzee adenovirus vector for long-term stability outside the deep-freeze cold chain.

Summary

A freeze-dried chimpanzee adenoviral (ChAd155) RSV vaccine retained functional potency within acceptable limits (<0.3 log loss) after five years at 5°C, with preserved efficacy in a murine RSV challenge after two years and acceptable safety in rabbits. This demonstrates a practical path to cold-chain–light vaccine deployment for respiratory pathogens.

Key Findings

• Lyophilization resulted in only 0.12 log potency loss; 5-year stability at 5°C remained within <0.3 log loss.
• Efficacy was preserved in a murine RSV challenge after two years of storage.
• Acceptable safety profile was confirmed in a rabbit toxicology model.
• Capsid integrity, particle content, and DNA release remained stable over prolonged refrigeration.

Clinical Implications

Cold-chain–independent storage of adenoviral vaccines could expand access, enable stockpiling at refrigerator temperatures, and accelerate deployment for respiratory pathogens including RSV and pandemic threats.

Limitations

• No human clinical immunogenicity/effectiveness data presented.
• Findings demonstrated for a specific vector (ChAd155) and antigen; generalizability to other constructs requires testing.

Future Directions

Assess immunogenicity/effectiveness after long-term refrigerated storage in humans; extend lyophilized platform to other adenovectors/antigens; evaluate field logistics and cost-effectiveness in LMIC settings.