Precision dosing of recombinant vaccinia vaccine via pillar-guided microneedle patch confers SARS-CoV-2 immunity

Recent advances in microneedle array patch (MAP) technology have highlighted its potential for efficient and accessible vaccine delivery. In this study, we developed a pillar-guided MAP (PG-MAP) loaded with a recombinant vaccinia virus (r-DIs-S) expressing the SARS-CoV-2 spike (S) gene. Our fabrication method enabled precise localization of a high viral titer (> 9.4 ± 1.8 × 10⁶ PFU per patch), as verified by plaque assay. In vivo immunization in mice demonstrated that the r-DIs-S-loaded PG-MAP elicited robust S-protein-specific IgG and neutralizing antibody responses. Upon SARS-CoV-2 challenge, all PG-MAP-immunized mice survived and maintained their body weight, whereas the control groups experienced severe results. These results demonstrated that the PG-MAP platform enables precise dosing, maintains viral stability, and induces potent protective immunity, offering a promising alternative for decentralized, minimally invasive vaccination strategies against emerging infectious diseases.