Vaccination programs are essential to the control of disease. The World Health Organisation (WHO) vaccinates nearly 80% of the children born today against the six killer diseases: polio, diphtheria, tuberculosis, whopping cough, measles and tetanus. However, the WHO’s efforts are often severely hampered by the need to keep vaccines refrigerated. Now, scientists at Oxford University, UK have discovered a solution (Alcork et al, 2010).
How Does the New Method of Vaccine Storage Work?
The sugars sucrose and trehalose are commonly used as stabilizing agents for biological products. Their preservation properties have been further explored in this study by mixing them with the unstable vaccine. The mixture is then left to dry on a membrane until the syrup mixture has solidified on the membrane. This preserves the vaccine contained within the mixture and prevents it from drying out in the heat. Rehydration is achieved when water is applied. If the membrane is contained at the end of a syringe, introducing water into the syringe would release the vaccine and the patient could be injected.
Virus-based vaccines are particularly vulnerable to a rise in temperature. Researchers found that two such vaccines could be stored for up to six months at 45 degrees C without degradation and up to a year at 37 degrees C with minimal losses.
Successful application of this sugar preservation process to sensitive virus-based vaccines suggests that it could be applied to other types of vaccines and equally sensitive biological reagents, such as antibiotics. The beauty of this method is that it would be cheap and easy to use at any stage in the life of a vaccine from transportation to storage.
Prospects for Future Work on Malaria and AIDS Vaccines
This research represents the first time a live-virus vaccine has been kept alive after exposure to high temperatures. Plans to scale up this novel method of vaccine storage are underway. In countries where infrastructure (including efficient transportation and/or refrigeration facilities) is poor, vaccination programs struggle to succeed. Researchers hope that by reducing the cost of stabilising vaccines more children will be vaccinated in the future.
Similarly, this method may aid the development of vaccines against malaria and HIV-AIDS. To make vaccines against these diseases, researchers are using live ‘carrier’ viruses. After disabling the viruses, such that they can infect the body but not reproduce, the viruses are modified to carry genes which induce immunity. However, the viruses must stay alive to be effective. This new method of stabilisation may help overcome their sensitivity to heat.
Reference
Alcork R et al. "Long-term thermostabilisation of live poxviral and adenoviral vaccine vectors at supra physiological temperatures in carbohydrate glass." Science Translational Medicine 2010Feb 17;2(19):19ra12.
Catherine Whitlock - After some fun years in medical research poring over a microscope, I now write about the scientific wonders that others have magnified.I ...
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