Fear of vaccines has allowed a host of diseases, including measles and whooping cough, to re-surface around the world in recent years. However, the key issue isn’t vaccine safety, it’s vaccine delivery—how we actually get vaccines to, and into, people in order to improve global health.
Indeed, even though vaccination (and the health benefits that result) have increased in most developed countries, and become more prevalent in some developing countries, vaccination coverage still varies widely for different racial and ethnic groups and educational levels, as well as for high-risk populations.
This disparity in coverage may, at some level, have to do with vaccine fears; but, for the most part, it’s a result of less-than-optimal vaccine delivery.
Shipping vaccines around the world
There are two basic issues here. And the first one is transportation. Let’s say, for instance, that an effective vaccine is developed in Europe, the United States or India for use in African villages. Right now, it’s extremely difficult to get that vaccine delivered to the people who need it in a stable and undamaged state.
We believe you can have the best vaccine in the world, but if it’s damaged during the delivery process, it does no good. That’s why we’ve been working on a thermostable tuberculosis (TB) vaccine that’s resistant to damage from excessive heat or cold. Part of this technology includes the process of lyophilizing—or freeze-drying—the vaccine to increase its shelf life and allow successful shipment all over the world. First used commercially during World War II to stabilize temperature-sensitive blood serum for transport, freeze-drying is now used for a variety of products to achieve a temperature-stable shelf life. Thermostable vaccines could have great economic as well as health benefits.
According to experts from Doctors Without Borders, the need to maintain vaccines in a temperature-controlled supply chain—known as the “cold chain”—all the way to the patient is one of the biggest barriers to effective vaccination, particularly during the last stretch that takes the vaccine to the most remote areas.
Science helps explain this, because vaccines lose potency over time, with the rate of potency loss related to temperature; as of today, used vaccines have a shelf life of two years or longer only if they are continuously stored at refrigerated conditions of 36-46 degrees Fahrenheit.
Another aspect of this challenge involves the composition of next-generation vaccines, which contain both an antigen (a non-infectious piece of a pathogen that the immune system learns to attack) and an adjuvant (substances added to vaccines to enhance the ability of antigens to stimulate the body’s immune response).
The two components are now often kept in separate vials that must be mixed in exact proportions just before the vaccine is administered. But the lyophilizing process mentioned above could help us ship vaccines to just about every continent without the necessity of separate and inefficient antigen/adjuvant vials that add a potential element of risk for the patient. All it would take would be a little sterile water to reconstitute the vaccine on site, ensuring that a vaccine is still effective when it is delivered, even to the most remote parts of the world.
The bottom line is that we can help a lot of people if we deliver a thermostable TB vaccine. According to the latest data, TB-causing bacteria infect an estimated one-third of the global population; and, in 2013, approximately nine million people developed active cases of TB illness.
Moving beyond hypodermic needles
The second vaccine delivery issue revolves around injection. Let’s assume that we had a massive flu outbreak today, or a pandemic. Masses of people would, in all probability, flock to health care centers to get a flu shot vaccination, straining the facilities and even creating chaos in the process.
Our idea is to ultimately produce a one-dose vaccine that people could safely and effectively give themselves using a simple, painless patch that arrived in the mailbox. Using it would be just like putting a bandage on your skin.
NanoPass Technologies has developed this technology using tiny micro-needles. In addition to ease of use, the micro-needle technology may also improve the immune response of seasonal flu vaccines using smaller doses, because it provides targeted delivery of the vaccine to specialized cells of the immune system. Micro-needles inject vaccines directly into the region of skin where cells responsible for detecting foreign agents live; this means there could be a quicker immune response.
There are other important uses for the micro-needle technology, too.Working with researchers at the University of Washington, for example, researchers here at IDRI have come up with a biodegradable micro-needle patch that can test a person for TB. This affordable and innovative solution—the first time micro-needles have been deployed as a diagnostic—would replace the current test for TB, which involves inserting a hypodermic needle into a person’s arm using a very precise angle and depth.
One of the problems with today’s TB test is that it’s difficult to administer and often yields inaccurate results. With a micro-needle test, there’s little room for user error, because the depth of delivery is determined by the micro-needle’s length (roughly 1/40th of an inch), rather than the needle-insertion angle.
Gaining acceptance and adoption
Improving global health in the 21st century will require safe and effective vaccines based on a variety of breakthrough technologies. But cutting-edge delivery devices, processes—including, in some cases, transferring technologies that allow vaccines to be rapidly developed in the countries where vaccines are needed most—and systems must be an essential part of each and every one of these new solutions going forward. In the end, the vaccines with the best delivery mechanisms will be accepted and adopted as they become the true difference-makers all over the world.