No one likes needles. Now there’s another option. A group of scientists in Japan have found that a vaccine patch with microneedles called MicroHyala works as well as a traditional injected influenza vaccine.
Microneedles have been tested before in humans, but they have previously been made from metal or silicon. Vaccines administered by these microneedles have not produced good immune responses, and the microneedles can break off in patients’ skin, causing irritation and infection.
The MicroHyala patch has microneedles made from hyaloronic acid which is a natural part of our skin and dissolves in skin over time (see image above). The main benefits of the vaccine patch are that it is painless, so people will be more willing to have a patch vaccine rather than an injected vaccine, and the patch is a dry solid so is more stable at room temperature than a traditional liquid vaccine. But to be able to use patch vaccines, they must be at least as safe and effective as injected vaccines.
This was only a small study. Forty healthy middle-aged men received either an injected flu vaccine containing three flu strains (A/H1N1 and A/H3N2 and B) or a microneedle patch embedded with the same flu strains. The patch group had the patch on for six hours. After the patches were removed, scientists checked them under the microscope and counted how many microneedles had dissolved and how many remained. Over 50% of the microneedles dissolved in all patients (see image).
This evidently provided enough flu protein to cause an immune response in patients because the scientists found that patients in the patch group had the same level of antibodies against the A/H1N1 and A/H3N2 flu strains and more antibodies against the B strain than those who received a traditional needle vaccination. So the patch was actually more effective than the injected vaccine.
Even though the patch is painless, it did cause skin redness and swelling in all patients. However, these side effects resolved completely over time.
So the patch appears to be safe and effective. It is also easy to use so can be administered by non medical people. Therefore the patch could be a great way to get vaccines to areas that have poor access to medical facilities. But only if the patch vaccine remains stable at room temperature over long periods of time. So the scientists tested this by storing the patches at four, 25 or 40 degrees celsius for six months. They found that the level of flu protein in the patches was stable over six months at all temperatures. They then dissolved the protein from the patches and injected it into mice. Two of the three strains of flu from all the patches caused a good immune response in mice. The third strain recovered from the 40 degree patch did not cause an immune response. Overall these results show that the patches are relatively stable at room temperature over six months of storage.
So the vaccine patch may be the answer to getting vaccines to more people around the world. It remains to be seen whether the patch can be used to administer other treatments.
The Scientific Paper: