Flu vaccination is critical for vulnerable populations who are at a higher risk of hospitalisation or death from infection and its complications, particularly the very young and the elderly. Nevertheless, low rates of vaccination with the conventional needle-and-syringe method persist, with the most common reasons attributed to needle phobia, limited access in low income regions, and the inconvenience of travelling to the clinic with the associated time and cost of administration by a medical professional.  

A new phase I clinical trial published in the Lancet, led by Dr. Nadine Rouphael at Emory University, showed that an influenza vaccine delivered by a dissolvable microneedle patch produced a protective immune response similar to intramuscular injection. The study complies with FDA mandated thresholds for clinical development, and could therefore provide an alternative to hypodermic administration.

The patch--which looks like a sticking plaster—is embedded with microneedles made of water-soluble polymers combined with an active influenza antigen in a formulation previously reported in 2015 ¹.  After being stuck onto the back of the wrists of participants, the microneedles dissolved into the skin within minutes, delivering the vaccine.   The encouraging news for those who dislike needles is that compared with intramuscular injection, pain was less frequent and severe, and the patch was preferred by over 70% of participants despite some reporting mild, local skin reactions.  The microneedles are too small to penetrate deep enough into the skin to hit pain receptors.  Self-administration, which offers greater convenience, was just as effective at delivering the same dose as administration of the patch by a healthcare worker. Because the plaster can be peeled away and discarded by the patient, there is also the prospect of a reduction in sharps management.  Other advantages include greater safety (by reducing needle stick injuries), and lower costs, as the trial showed that vaccine potency was retained for 12 months without refrigeration, offering the prospect of eliminating the need for a cold chain. 

Phase I clinical trials are designed to assess safety only, and the authors note that the trial was not powered to demonstrate differences in immunogenicity and efficacy between the microneedle patch and conventional hypodermic delivery.  At this stage, the improved immunogenicity and efficacy of the microneedle patch can only be inferred by evidence from pre-clinical animal studies, in which the stronger  cellular responses to inactivated influenza virus compared with intramuscular injection are due to the large network of antigen-presenting cells in the skin ^2,3.

Further development and progression to late stage clinical trials will confirm whether the stick-on microneedle patch can deliver pain free, more convenient and effective vaccines at lower economic cost, so that one day, when your doctor asks you if you want a flu jab—you can tell them they can stick it. 

Highlighted paper

Rouphael, N.  et al. The safety, immunogenicity, and acceptability of inactivated influenza vaccine delivered by microneedle patch (TIV-MNP 2015): a randomised, partly blinded, placebo-controlled phase 1 trial. Lancet 2017;(Jun). 

Further reading

1) Vassilieva, EV. et al. Improved immunogenicity of individual influenza vaccine components delivered with a novel dissolving microneedle patch stable at room temperature. Drug Deliv Transl Res. 2015 Aug; 5(4): 360–371.

2) Marshall S. The success of microneedle-mediated vaccine delivery into skin. Hum Vaccin Immunother. 2016 Nov; 12(11): 2975–2983.

3) del Pilar Martin M. Local response to microneedle-based influenza immunization in the skin. mBio 2012 Mar 6;3(2):e00012-12. 

Banner image reproduced from The Lancet, Vol. number, (in press) Rouphael, N.  et al. The safety, immunogenicity, and acceptability of inactivated influenza vaccine delivered by microneedle patch (TIV-MNP 2015): a randomised, partly blinded, placebo-controlled phase 1 trial, Pages No (in press), Copyright (in press). DOI: http://dx.doi.org/10.1016/S0140-6736(17)30575-5 with permission from Elsevier.