PATH is exploring ways in which jet injector technology could facilitate new vaccination strategies. Frequently asked questions about the technology are answered below.

What is jet injection?

Jet injectors work by using pressure (either from a spring, a gas cartridge, or some form of external power source) to send liquid into the body. The liquid travels in a narrow stream so quickly that it is able to pierce the skin and travel as deep as the muscle—reaching the same tissues that a traditional needle would.

What are disposable-syringe jet injectors (DSJI)?

A DSJI is a jet injector that uses single-use needle-free syringes. One syringe is used for each injection and is then discarded—it cannot be reused. Older models of jet injectors reused the same skin-contacting pieces on different patients, which presented a risk of disease transmission through transference of body fluids, called cross-contamination. DSJIs improve the safety of immunizations and the safety of those administering them.

What is “intradermal vaccination?”

Injections are given into different tissues in the body, depending on how the drug is supposed to work. These tissue layers are intradermal (ID), subcutaneous (SC), and intramuscular (IM). SC and IM are the most common for vaccines. ID injections—which go just under the skin—are also frequently used for tuberculosis tests and some vaccinations, such as BCG and rabies. There is a great deal of interest in ID injections for vaccines, since the skin plays an important role in the immune system and may respond to smaller doses of vaccine than other tissues.

How do jet injectors achieve intradermal injections?

Depending on the device, the depth of a jet injection is determined by the pressure of the liquid stream, the diameter of the syringe orifice, or the distance of the orifice from the skin, as well as the user’s technique. Injecting into the thin dermal layer of the skin with a standard needle and syringe can be difficult; using a jet injector may make it easier for health care workers to deliver reliable intradermal injections.

What is the goal of PATH's DSJI project?

By scientifically evaluating effective, safer, and adoptable technology for delivering vaccines in the developing world, PATH will provide new data to advance the knowledge and work of the global health community. In short, we will learn if DSJIs have the potential to provide safe and affordable vaccinations around the world.

What are key objectives of the DSJI clinical trials?

Through clinical trials of vaccines given using jet injection and pilot program introduction activities, we hope to:

• Demonstrate acceptability, sustainability, and cost-effectiveness of DSJIs.
• Demonstrate clinical feasibility of intradermal vaccine delivery.
• Advance the potential of DSJIs appropriate for developing-country use.

Are the DSJI clinical trials testing the effectiveness of new vaccines?

No, the DSJI clinical trials are focused solely on the technology used to deliver the vaccine, not the vaccines themselves. However, some clinical trials will test the potential of DSJI technology to protect patients from disease with a reduced dose of certain vaccines delivered intradermally. Successful trials may demonstrate that lower dosages can protect patients, and, as a result, save on immunization costs overall.

Why was Brazil selected as the country for the DSJI clinical trials?

Middle-income and emerging-economy countries, such as Brazil, represent an optimal scenario for launching manufacturing of DSJIs and introducing them into an immunization program.  Brazil as a site offers the following advantages: public-sector vaccine manufacturers that have pledged support of the DSJI project, a WHO-recognized national regulatory authority, a strong immunization program, and existing in-country partnerships with PATH. Brazil also has a history of using previous-generation jet injectors in its immunization campaigns and is interested in exploring new developments in the technology class.

How will PATH work with government and health leaders in Brazil to implement DSJI use if the clinical trials show positive results?

PATH works collaboratively with our global, local, and philanthropic partners to advance the adoption of new technologies. During the course of the project, PATH will work with in-country government and health leaders to communicate the potential benefits (and costs) of the technology, understand the willingness to pay for the DSJI technology, and determine how the DSJI technology can be incorporated into the immunization program in Brazil. A pilot introduction study conducted by PATH should help gather much of this information.

What are some of the risks associated with DSJI devices?

The risks associated with DSJIs are similar to those of a needle and syringe and are expected to be rare. There may be redness, pain, irritation, and/or bruising at the site of injection. In rare instances, a laceration may result if the person moves at the moment of injection.

How are DSJI devices superior to needle injections?

DSJIs can improve injection safety in developing countries by reducing the reuse of potentially contaminated needles and syringes, preventing needlestick injuries, and reducing the overall burden of sharps waste. Wit han estimated 50% to 70% of injections in the developing world considered unsafe, DSJI may provide a safer alternative to injections given with needles.

Are DSJI devices more expensive than needles and syringes?

As the production of DSJIs comes to scale, DSJIs may be comparable in cost to administering immunizations with needles and syringes when all immunization-related costs are taken into account, including reducing sharps waste, preventing needlestick injury, and reducing vaccine wastage.

What advances have been made with DSJI technology to prevent cross-contamination?

DSJIs improve the safety of immunizations and the safety of those administering them in developing countries. New jet injectors solve the problems of previous generations of devices which had the potential for cross-contamination of the nozzle orifice. On these redesigned devices, new, sterile, single-dose, needle-free syringes are used for each injection; the syringe is discarded after a single use, preventing cross-contamination between patients. The simple design allows for safe administration by many levels of health care professionals; in addition, no change in vaccine formulation is required.

Can DSJI devices reduce the amount of vaccines needed for protection from disease?

DSJIs can deliver vaccines intradermally, which for some vaccines could reduce the volume of vaccine required by up to 80% and has been shown to be effective against some diseases like rabies and influenza. Additional studies are underway to better understand this method. Though this type of injection can be done with traditional needles and syringes, DSJIs may be able to deliver vaccines at the intradermal depth more simply and efficiently.