Microneedle-mediated intradermal delivery of Bacille Calmette-Guérin (BCG) vaccines for single-dose tuberculosis vaccination

Tuberculosis (TB) remains a highly lethal infectious disease. The primary preventive measure is Bacille Calmette-Guérin (BCG), a live attenuated vaccine. However, the current intradermal vaccination method with 10-dose vials faces challenges such as inadequate infant injection, inaccurate dispensing, and unstable storage. Researchers have explored Microneedle (MN) technology to address these concerns as a transdermal vaccine delivery approach. MNs offer painless administration, convenience, improved immunogenicity, and vaccine stability. This study aimed to develop a coated MN system using a micro-dispensing technique at a low temperature (4 °C) and specific excipients for precise dosing and vaccine viability enhancement. Long-term storage stability revealed enhanced storage stability of the BCG-coated MN (BCG-MN) vaccine, maintaining a survival rate of over 60 % for 8 weeks at -20 °C. In vivo, vaccination tests using BCG-MN patches on guinea pigs exhibited no adverse reactions. Moreover, the BCG-MN vaccine patches demonstrated superior immune response compared to injections, suggesting that this BCG vaccine-coated MN platform has the potential as a single-dose TB vaccination technology, offering precise dosing control and enhanced immune effectiveness with high storage stability.