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Contact: Amy Wales, PATH, 206.285.3500, awales@path.org.

A recent study published in Vaccine offers promising results for preventing vaccine damage

Seattle, WA, January 21, 2009—Scientists at PATH have developed a formulation method that protects vaccines from freeze damage and represents a critical step forward in ensuring the world’s children are receiving fully potent vaccines.

PATH scientists, in collaboration with colleagues at the University of Colorado, published findings in the most recent issue of Vaccine (volume 27, issue 1) that describe how the method preserves the effectiveness of specific types of vaccines even after repeated exposure to freezing. This formulation method is applicable to vaccines containing aluminum adjuvants—including hepatitis B, diphtheria, tetanus toxoid, and pertussis vaccines. In addition to ensuring vaccine effectiveness, the prevention of freeze damage also means less vaccine wastage, which often occurs when health workers dispose of vaccines suspected to have been exposed to freezing.

Addressing high rates of exposure to freezing

Vaccines are powerful public health tools that save an estimated three million lives per year. World Health Organization guidelines recommend that all vaccines (except oral polio vaccine) be stored at 2°C to 8°C. These temperature requirements necessitate use of a vaccine cold chain—a global distribution network of equipment and procedures for maintaining vaccine quality during transport and storage. Systematic literature reviews of 25 published and 10 unpublished articles on the transportation and storage of vaccines in both developed and developing countries indicate that vaccines are frequently exposed to freezing temperatures, rendering considerable vaccine damage and wastage.

PATH scientists worked to address these issues in the lab by adding freeze-protection stabilizers, such as glycerin, polyethylene glycol 300, or propylene glycol, to a number of vaccines containing aluminum adjuvants. These stabilizers all have a long history of use in many other human medications with excellent safety records. Findings published in Vaccine show that just a small amount of one of these stabilizers can effectively protect these vaccines from the damage often caused by accidental freezing. The development of the formulation method and the research described in the published study were conducted in conjunction with PATH’s broad project work in vaccine stabilization, funded by the Bill & Melinda Gates Foundation.

Putting technology in manufacturers’ hands

To date, PATH and collaborators have completed additional laboratory and preclinical studies validating the science and technology behind freeze-stable formulations. PATH has placed this technology in the public domain so that vaccine manufacturers worldwide can utilize the approach in their formulations. Two commercial vaccine producers are in the process of applying the formulation approach to existing vaccines. Altogether, freeze-stable formulations translate into promising measures for preventing vaccine damage caused by accidental freezing.

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