Transdermal microneedles for the programmable burst release of multiple vaccine payloads

Repeated bolus injections are associated with higher costs and poor compliance and can hinder the implementation of global immunization campaigns. Here, we report the development and preclinical testing of patches of transdermal core–shell microneedles—which were fabricated by the micromoulding and alignment of vaccine cores and shells made from poly(lactic-co-glycolic acid) with varying degradability kinetics—for the preprogrammed burst release of vaccine payloads over a period of a few days to more than a month from a single administration. In rats, microneedles loaded with a clinically available vaccine (Prevnar-13) against the bacterium Streptococcus pneumoniae induced immune responses that were similar to immune responses observed after multiple subcutaneous bolus injections, and led to immune protection against a lethal bacterial dose. Microneedle patches delivering preprogrammed doses may offer an alternative strategy to prophylactic and therapeutic protocols that require multiple injections.