How an award-winning ensilication technology could remove the need to refrigerate life-saving vaccines
MOTHERHOOD changes people, irreversibly. For me it was not just becoming a parent, but it also influenced the direction of my research. When my daughter was only a few days old, I took her to the doctors to be vaccinated with BCG vaccine (against tuberculosis). The doctor took the vaccine out of the fridge and administered it directly. That’s when I asked: “why must vaccines be refrigerated?”, and then the natural follow-up question, “can I help to make them stable at room temperatures?”
From then on that second question became almost an obsession for me. At the time I was already a Royal Society University Research Fellow, working on developing porous alumino-silicate materials. I decided to dedicate some of my time to developing an idea – applying silicates (materials made of amorphous silica, SiO2) to the proteins within vaccines, to render vaccines stable at room temperatures. Silica is a great material, it is biocompatible, non-toxic, cheap, abundant and easy to manipulate.
Why is this important not just for me but for people all around the globe? I suspected that even in the 21st century, when we have very effective vaccines, people are still dying from vaccine-preventable diseases. But I was wholly unprepared for the raw statistics surrounding vaccination. Despite the sterling job the WHO and UN are doing on vaccinating children around the world, there are still enormous problems. Thousands of children under the age of five still die every year from tetanus, measles, pertussis, rotavirus, and other diseases which are so easily prevented by vaccination. Low-income countries have orders-of-magnitude lower vaccination rates compared to developed countries.
Why we are failing in protecting people, and in particular children? The problems with vaccine availability are very complex – involving conflicts, economic downturns, political issues, natural disasters, religious views, problems with physical delivery and their cost, to name but a few. Many of these issues make vaccine availability impossible in some regions around the world. Physical delivery is a particular problem because many vaccines spoil at temperatures above 8oC, as the proteins which make up the vaccine unfold and cannot re-fold back. Think of a boiled egg – once boiled it cannot be brought back to its raw state, because all proteins inside an egg unfold and tangle up while heated. Most vaccines also cannot be frozen as they would lose their potency; the ice crystals forming in the formulated liquid during freezing are also disruptive to protein structures.
This means that vaccines have to be stored and transported at temperatures of 2–8oC at all times – the so-called “cold chain”. In developed countries it is not a big problem, as there are specialised fridges and electricity available 24/7 allowing for this cold chain to be maintained in hospitals, GP surgeries, storage facilities and transport vehicles. In many developing countries, this is not the case as there may be no cold-storage equipment, or cold-storage transport. Sometimes there is no electricity, and roads and other infrastructure are inadequate to support the cold chain for vaccine transport and delivery.
WHO estimates that anywhere between 30–50% of vaccines are discarded today because of cold-chain failures. Efficient alternatives to refrigeration would help us to make vaccines widely available
Because of problems with electricity and equipment, many vaccines are wasted. WHO estimates that anywhere between 30-50% of vaccines are discarded today because of cold-chain failures. It is also possible that some people in developing countries are receiving inactive vaccines because of cold-chain failures. The cold chain as a solution for vaccine storage and delivery was introduced by WHO in the 1970s, and it has remained unchanged for almost 50 years. Efficient alternatives to refrigeration would help us to make vaccines widely available. Even incremental improvements in vaccine coverage can have a dramatic effect on public health, as once coverage exceeds about 85%, “herd immunity” provides protection to unvaccinated individuals.
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