Vaccine microarray patch self-administration: A preliminary study in adults 50 years of age and over

Introduction: We assessed the safety, performance, acceptability, and usability of the High-Density Microarray Patch (HD-MAP) for vaccination in adults aged 50 and over. Methods: This study was a single-centre, open-label, single-arm intervention in healthy adults aged 50+. HD-MAPs (vaccine-free) were applied by a trained user and self-administered. Participants received one excipient-coated HD-MAP to the volar forearm (FA) and the upper arm (UA) administered by a trained user. Participants then self-administered a HD-MAP to the FA and UA. Application sites were compared for skin response. Participants completed an online survey and participated in a semi-structured interview on acceptability and usability. Analyses were undertaken using descriptive statistics. Interviews were coded in NVivo 12 and subject to thematic analysis. The study occurred from 8 September 2021 to 15 February 2022 in Brisbane, Australia. Results: Of 44 participants, 43 % (n = 19) were male, and 57 % (n = 25) female. The HD-MAP was well-tolerated, with no treatment-related serious adverse events. The increase in transepidermal water loss following self-administration was similar to that observed for trained user administration (UA: 7.5 fold vs 6-fold, FA: 6.1-fold vs 6.6 fold). Fluorescent dermatoscopy confirmed that HD-MAPs engaged with the skin surface and that self and trained user administrations were similar. All participants found the HD-MAP applicator easy to use. 82 % of participants preferred "vaccination" by HD-MAP should its efficacy be proven equivalent to intramuscular injection (IM). Participants reported high acceptance of the resulting transient marks on the skin (82 %). 98 % of participants agreed that self-administration of the HD-MAP at home, without supervision, was highly preferable for its convenience. Conclusion: HD-MAPs were safe in adults 50+ years, and performance was effective, regardless of administrator. Participants preferred the HD-MAP for its ease of use and convenience in self-administration. This vaccine delivery method shows promise for future implementation for this population.