Debra Kristensen

Debra Kristensen focuses on ensuring that effective vaccines reach their targets.

What's the best way to deliver an effective vaccine?

On the third floor of PATH’s Seattle headquarters, adjacent to the laboratory and product development shop, highly specialized teams are working to solve a critical piece of the vaccine delivery puzzle. They’re discovering how to safely and effectively distribute, store, and administer vaccines in places with weak health and transportation infrastructure, unreliable electricity, and minimally trained health workers.

Using the latest technological and scientific advances, the teams’ goal is to make it easier for people to be vaccinated, while at the same time improving the safety and effectiveness of vaccines and vaccine distribution systems.

Debra Kristensen, group leader for vaccine technologies at PATH, knows that even when a vaccine is widely available, many conditions can sabotage its effectiveness. Luckily, her teams have devised innovative ways to avoid that damage.

Products in the pipeline

Debra shares some successes and promising products in the pipeline:

Photo from 'Technologies for vaccines' slideshow.

Innovative solutions make vaccines safer and accessible. View the slideshow.

Temperature extremes can irreparably damage vaccines, yet we know that vaccines are frequently exposed to both heat and freezing temperatures in developing countries—and even here in the United States. We’re pursuing a variety of solutions, ranging from developing equipment for low-resource settings to store vaccines at optimal temperatures to improving vaccines so they’re better able to withstand fluctuating temperatures.

Exposing vaccines to freezing temperatures during transport and storage is particularly a problem with vaccines that contain aluminum salt adjuvants. These boost a vaccine’s ability to produce an immune response, but they also increase the vaccine’s sensitivity to extreme cold. Thinking creatively, one of our lead scientists developed a stabilization formula that can be added to vaccines to make them resistant to cold. This vaccine freeze protection technology is inexpensive, safe, and can be incorporated into new vaccines as well as existing vaccines. And it’s just one of the vaccine stabilization technologies we’re researching. By making vaccines more robust, we aim to ensure they are as effective when they are delivered as when they were produced.

Immunization without shots

The pipeline includes innovative delivery methods that go beyond regular intramuscular injection, as Debra outlines:

We’re also working on new methods to administer vaccines. For example, diseases caused by pathogens that enter the body via the mucosa—the mucous tissue lining the nose and mouth as well as reproductive and gastrointestinal tracts—can be difficult to target with vaccines. Oral drops are the easiest to administer, but many vaccines are compromised by stomach acids.

“No other group that I'm aware of spans the production-to-use spectrum like we do.”

With collaborators, we are developing and testing a unique formulation that may solve this problem. Called a sublingual gel, it begins as a liquid solution, but when it’s dropped under the tongue, it turns into a gel. The vaccine is easily absorbed by the thin tissue under the tongue, and because it’s a gel, it won’t be swallowed. Now in the testing phase, it could potentially help to prevent any disease that passes through the mucosa, including diarrheal diseases, HIV, and polio. The benefits could be great, and we’re very hopeful.

Another important area of ongoing research is intradermal delivery. The upper layers of the skin play an active role in the immune system, and delivering vaccines to these tissues may require smaller quantities of vaccine than needed for regular intramuscular injection. Technologies we’re investigating range from jet injectors to microneedles, which could potentially allow for self-administration of vaccine.

Development and delivery

Debra describes how we move through the full spectrum of development to delivery to match vaccines with the right technologies:

PATH plays a unique role in this work. We develop vaccines and we’re deeply involved in the introduction and delivery of vaccines. No other group that I’m aware of spans the production-to-use spectrum like we do. And as a nonprofit, we have no vested interest in any particular technology. We can evaluate a technology and then move it forward or not based on its performance and ability to meet developing-country needs.

Because of our partnerships with biotech firms, vaccine manufacturers, and university labs, we’re also able to play a facilitative role—marrying the appropriate technology with the appropriate vaccine. Ultimately, we hope that the vaccines of tomorrow will integrate the best of these technologies, making vaccination in developing countries safer, simpler, and more effective.

Next  Maintaining effectiveness

Photos: PATH/Scott Areman.