In combination with greater cleanliness and antibiotics, vaccines have played a key role in improving health and longevity. In the Western world, we take vaccines for granted. Refrigeration is readily available to keep vaccines within a narrow temperature range from manufacturing to usage. In the developing world, this infrastructure often does not exist. The World Trade Organization has estimated that maintaining the ‘cold chain’ would cost U$200-300 million annually, a sum that could be used instead to fund vaccine doses and delivery, along with other preventative health care.
Aside from cold, another natural way to preserve organic substances is dehydration. Unfortunately, dehydration can cause damage to the folding structure of proteins, critical to the protein’s proper function. A number of species such as the African midge, brine shrimp and the resurrection plant are able to survive dehydration by entering ‘anhydrobiosis’ – a state in which the organism displays no metabolic activity yet
can recover when water becomes available. The ‘trick’ involves cells generating a sugary substance such as trehalose. Although the exact details are still being studied, the sugars appear to replace water and also form an amorphous glassy matrix that slows protein unfolding.
Dr. Bruce Roser is a pioneer in exploring ways of storing vaccines without refrigeration. Inspired by organisms that undergo anhydrobiosis, he co-founded Cambridge Biostability Limited in 1998 and is actively developing technologies for stabilizing vaccines and other drugs. After mixing the vaccine with water-soluble sugar glasses, the water is removed and the result is formed into microspheres through spray-drying. These microspheres can be mixed with an inert anhydrous liquid and stored for extended periods at ambient temperatures. The combination can be directly injected without requiring that the dry vaccine be reconstituted with water in a sterile environment. Dr. Roser is also exploring how the sugar glass concept could be applied to improve cryopreservation of tissues and organs.
The first person survival story of John Dau one of the Sudanese Lost Boys.