Many vaccines, such as those for Hep A and B, HPV, MMR and rabies, need several booster doses to achieve maximal immunological protection. Booster doses add to the complexity of vaccine administration, especially when used in large vaccination campaigns in the developing world. Therefore, anything which simplifies vaccine administration and reduces the need for multiple medical consultations is likely to have a major beneficial impact on future global health campaigns. If the prime-boost strategy could be replaced by a body depot, for example, it’s likely that vaccination coverage could improve for a number of diseases.
Researchers reporting in Advanced Functional Materials have been investigating a vaccine delivery system that uses a hydrogel implant to replace follow-up injections. The implant, a small hydrogel sphere placed under the skin, would then release additional doses of the vaccine once a patient swallows a fluorescein-containing pill. In the recent study in mice, the team incorporated human papilloma virus particles into the hydrogel mesh and implanted them in vivo. The mice then swallowed a pill containing fluoroscein, which acted as a trigger to dissolve the mesh and release the vaccine. The ‘remote-controlled’ release of the vaccine resulted in successful immunoprotection.
The team have also looked at the hydrogel implant method in hepatitis B vaccine administration, reported here in Nature Scientific Reports. In mice, the hydrogel depot was sensitive to novobiocin, allowing for a drastic simplification in repetitive vaccine delivery. “This material-based vaccination regime holds high promises to replace classical vaccine injections conducted by medical personnel by the simple oral uptake of the stimulus thereby solving a major obstacle in increasing hepatitis B vaccination coverage,” write the researchers.
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