Dose-sparing and intradermal applications
New approaches to bridging the gap
Some vaccines and essential medicines are too expensive for developing-country immunization programs. Others are subject to shortages or imperfect distribution systems. Any one of these factors can prevent people from accessing the health care products they need. PATH is exploring ways to bridge the gap.
A potential solution is intradermal (ID) delivery. The skin is an active player in the human immune system, particularly the shallow, upper layers. Delivering vaccines directly to these tissues can be very effective, potentially even more immunologically efficient than injection into the muscle or subcutaneous tissues. Research also shows that ID delivery with some vaccines can achieve the same results as intramuscular or subcutaneous injection using up to 80 percent less vaccine—helping to optimize the capacity of the cold chain, lower the cost of each dose, and enable immunization programs to stretch their vaccine supplies across more patients.
Despite these benefits, this dose-sparing approach is not yet universal—due in large part to the challenges associated with giving an ID injection using the Mantoux technique, which requires a traditional needle and syringe for ID delivery. Although it is considered the preferred method for delivering vaccines intradermally, the injection procedure is difficult to perform and therefore inconsistently used.
Novel tools to ensure effective delivery
PATH and our partners continue to explore the broader landscape of ID delivery, assessing and advancing a number of novel delivery technologies to improve the reliability and effectiveness of dose sparing. We focus on those vaccines of importance to developing-country immunization programs with which dose sparing has been shown to be effective, and may help to overcome shortage issues.
Highlights of PATH’s work on intradermal delivery devices include:
- Intradermal adapter. This technology makes it easier to administer conventional ID injections. The adapter functions like a plastic sleeve, standardizing the depth and angle of the injection with a traditional needle and syringe. For this reason, it holds promise for expanding the pool of health care workers capable of performing the Mantoux technique. The delivery technology could also have a particularly high impact in remote or underserved communities with limited access to health workers with specialist training. Visit our page on the ID adapter to learn more »
- Disposable-syringe jet injectors. In addition to making injections safer, disposable-syringe jet injectors (DSJIs) offer health workers a needle-free means to more simply and efficiently deliver vaccines intradermally. Depending on the device, the depth of a jet injection is determined by the pressure of the DSJI liquid stream, the diameter of the syringe orifice, or the distance of the orifice from the skin. In addition to the many other activities that PATH is advancing as part of our exploration of the DSJI technology for public health, we continue in collaboration with a variety of DSJI developers to assess and demonstrate the technology’s clinical and commercial feasibility as a reliable and cost-effective means of delivering vaccines intradermally. Visit our page on DSJIs for ID delivery to learn more »
- Microarray patches. Although still in development, these delivery technologies are specifically designed to access the intradermal cells. Some microarray patches (formerly known as microneedles) consist of tiny needles coated with vaccine or medication, leveraging the moisture in the skin to deliver the vaccine or pharmaceutical product directly into the intradermal layer. Hollow microneedles mounted on syringes have also been developed that can deliver liquid vaccines. All have shown great promise in preclinical studies, particularly with influenza and poliovirus vaccines. In partnership with two academic research institutes, PATH is working to create a microarray patch for self-administration. Visit our page on microarray patches to learn more »
- Electroporation. The administration of certain DNA vaccines via electroporation has been shown to result in 100- to 1,000-fold higher immunogenicity. In addition, some dual-depth electroporation technologies, configured for simultaneous ID and intramuscular delivery, elicit antibody and cellular immune responses superior to those achieved with hypodermic injections. PATH is assessing the opportunities and challenges of this delivery method as a means of administering vaccines and other therapies in routine and campaign health care settings. Visit our page on electroporation to learn more »