A safer, cheaper way to get vaccines where they are needed most

Injections without needles? It may sound too good to be true, but PATH and our commercial partners are bringing “jet injection” to developing-country immunization programs, where the technology will make it safer for kids to get their shots.

Jet injectors use air pressure rather than needles to deliver vaccine as a fine stream of fluid that passes through the skin and into the tissue. New and improved over older models that had some drawbacks, today’s jet injectors overcome many of the risks associated with injections in low-resource settings.

Injections that can cause infection

In the United States and other developed countries, injections are given by trained personnel who always use a new, sterile syringe readily obtained from a nearby, reliably stocked supply room. In the developing world, the very injections meant to prevent or treat disease can end up causing it instead.

Injections become unsafe when health workers reuse syringes and needles or lack the training they need to give injections the best way. In addition, systems for disposing of medical waste may be weak, and used needles may be gleaned from the garbage and resold—or may find their way into the curious hands of children.

At least 50 percent of injections given in developing countries are unsafe, putting people at risk of infection, such as HIV and hepatitis. Get rid of the needles, and you can go a long way in protecting both patients and health workers.

The next generation

Jet injectors hit the immunization scene in the 1960s and were used to give millions of injections over about a 20-year period; they helped eradicate smallpox. Unfortunately, they fell out of favor with public health officials in the 1980s, after they were suspected of spreading hepatitis. The need for a needle-free technology remained.

The problem was that older injectors administered multiple doses of vaccine from a single vial. New injectors use disposable cartridges—each containing a single dose of vaccine—that prevent the transmission of infection from one person to the next.

PATH has worked with several jet injector companies over the years; our current work is with Bioject Medical Technologies to advance one of the “second generation” jet injectors. Designed for use in developing-country clinics or large immunization campaigns, the jet injector is hand-wound, and vaccine under spring-powered air pressure penetrates the skin. We are collaborating with Bioject to finalize the design and conduct clinical testing. At the same time, we’re compiling evidence that demonstrates the jet injector will be cost-effective and practical in the developing-country context—and for the long term.

Market research in the field

Early feedback on the jet injector design features from people who will use the technology helped shape and refine the Bioject model. We conducted field assessments of the prototype in South Africa and Tanzania in 2004. After refining the design, we re-evaluated it in Brazil, India, and China in 2006, making important adjustments in response to the feedback we received each time.

Throughout the field assessments, we were heartened to find that health care workers were highly receptive to needle-free injection and immediately recognized the safety benefits. The main concern they had about the overall technology was, “When will it be ready?”

Changing the landscape of immunization

In addition to making injections safer, jet injectors may help make vaccines more available in developing countries. Jet injectors are able to consistently and reliably deliver vaccines intradermally (within the layers of the skin), a method that reduces the amount of vaccine required—by up to 80 percent! (Intradermal delivery with needles is an advanced technique that often isn’t practical in developing-country health care settings or during mass immunization.) With jet injection, less vaccine will be needed, and vaccine that is in short supply (some vaccines are supply-constrained because they are difficult to produce) can be spread further. With cost savings from reduced doses, health managers will be able to purchase more vaccine—and immunize more children—or put the money to use elsewhere.

Next PATH will conduct clinical trials to investigate the possibility of vaccination with reduced doses of vaccine, and we will continue to work with our private-sector partner to finalize the second-generation injector and integrate it into public health systems. By mitigating safety and cost issues, jet injection just might help overcome the social, economic, and health inequities that keep children in the developing world from getting the protection they need to lead healthy, productive lives.

Photo: PATH.