Could Dissolvable Microneedles Replace Injected Vaccines?
Eric is terrified. He stands outside the clinic and takes a few deep breaths before walking slowly through the automatic doors. The nurse reassures him as he takes a seat. But then he sees it: the needle. The blood drains from his head and he faints.
An estimated 1 in 5 people suffer from trypanophobia – a fear of needles – and studies suggest that around 1 in 12 people cite fear as their reason for not getting vaccinated. A new vaccine delivery system could solve this problem: dissolvable microneedle patches are simple to use, pain-free and effective.
Flu vaccines delivered using microneedles that dissolve in the skin can protect people against infection even better than the standard needle-delivered vaccine, according to new research published in Biomaterials. The authors of the study, from Osaka University in Japan, say their dissolvable patch – the only vaccination system of its kind – could make vaccination easier, safer and less painful.
Downsizing to address the needle problem
Most vaccines are injected under the skin or into the muscle using needles. While this is an effective delivery method, it requires medical personnel with technical skills and brings the risk of needle-related diseases and injuries. It also induces crippling fear in many people, often causing them to avoid vaccination.
The new microneedle patch is made of dissolvable material, eliminating needle-related risks. It is also easy to use without the need for trained medical personnel, making it ideal for use in developing countries, where healthcare resources are limited.
“Our novel transcutaneous vaccination using a dissolving microneedle patch is the only application vaccination system that is readily adaptable for widespread practical use,” said Prof. Shinsaku Nakagawa, one of the authors of the study and Professor of Biotechnology and Therapeutics at the Graduate School of Pharmaceutical Sciences at Osaka University. “Because the new patch is so easy to use, we believe it will be particularly effective in supporting vaccination in developing countries.”
The new microneedle patch – MicroHyala – is dissolvable in water. The tiny needles are made of hyaluronic acid, a naturally occurring substance that cushions the joints. When the patch is applied like a plaster, the needles pierce the top layer of skin without causing pain and dissolve into the body, taking the vaccine with them.
The researchers compared the new system to traditional needle delivery by vaccinating two groups of people against three strains of influenza: A/H1N1, A/H3N2 and B. None of the subjects had a bad reaction to the vaccine, showing that it is safe to use in humans. The patch was also effective: people given the vaccine using the microneedles had an immune reaction that was equal to or stronger than those given the vaccine by injection.
“We were excited to see that our new microneedle patch is just as effective as the needle-delivered flu vaccines, and in some cases even more effective,” said Dr. Nakagawa. “We have shown that the patch is safe and that it works well. Since it is also painless and very easy for non-trained people to use, we think it could bring about a major change in the way we administer vaccines globally.”
New approaches to vaccination
According to the World Health Organization, immunization prevents an estimated 2 million to 3 million deaths every year. The continued threat of pandemics such as H1N1 swine flu and emerging infectious diseases such as Ebola makes vaccine development and mass vaccination a priority for global healthcare.
Delivery methods that do not require needles are safer for the person administering the vaccine, more pleasant for the person receiving the vaccine, and potentially less expensive. The challenge is developing a delivery method that gets the vaccine into the body effectively.
Microneedles provide one such delivery method, and they can be made of various different materials. Previous research has evaluated the use of microneedles made of silicon or metal, but they were not shown to be safe. Microneedles made from these materials also run the risk of breaking off in the skin, leaving tiny fragments behind; dissolvable patches eliminate this risk.
For some diseases, vaccines may be more effective when they’re absorbed through the mucous membranes in the nose. For example, studies in mice have suggested that tuberculosis vaccines delivered through the noseare more effective than those that are injected, as they target the respiratory system.
Tuberculosis experts gathered in a workshop at the National Institute of Allergy and Infectious Diseases at the National Institutes of Health in Bethesda, Maryland, in April 2014 to discuss this approach. According to the meeting report, they “emphasized the need for greater support to further explore the potential for this delivery methodology, either alone or as an adjunct to traditional parenteral methods of vaccine administration.”
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