Developing technologies to prevent damage from heat and cold

The weather forecast calls for sunshine and temperatures nearing 95°F (35°C). This is decent weather for a bumpy motorcycle ride to a rural village in Ghana—unless you are transporting vaccine.

One of the biggest challenges to vaccine use in developing countries is temperature regulation. Overexposure to extreme heat or cold can ruin desperately needed vaccines. Also, the need to keep vaccines cold during storage and transport requires using scarce resources to cover costs for refrigeration equipment and special handling procedures.

To increase the reach of immunization programs in developing countries, PATH is advancing technologies to make vaccines stand up under the toughest conditions. We continually research methods to improve stability of existing vaccines for common childhood illnesses, such as measles, as well as new vaccines. We are currently focusing on three approaches:

• Spray drying of vaccines.
• Freeze stabilization.
• Formulation of vaccines to increase protection from heat damage.

Advancing technology development

Spray drying is a process previously used in the food industry to create instant drink mixes and powdered milk. PATH is adapting this process for use with vaccines that can be reconstituted for injection or administered orally or through inhalation. We have established an in-house spray-drying laboratory to conduct feasibility studies with various vaccines. We have already made substantial progress using this method with meningococcal A vaccine and are now testing the viability of spray drying oral vaccines for bacterial diarrheal diseases.

Freeze stabilization is a method developed by PATH that uses common ingredients to guard vaccines against extreme cold. PATH has successfully applied this technique to protect hepatitis B, diphtheria, pertussis, and tetanus vaccines against freezing temperatures.

PATH is also advancing work on formulation of liquid vaccines to maximize heat stability. One of PATH’s partners, for example, has developed a method that uses stabilizing and buffering ingredients to protect vaccines from heat damage. PATH has already applied this approach effectively with hepatitis B vaccine.

Moving from research to adoption

To move these stabilization methods from the laboratory to use in immunization programs in developing countries, PATH is collaborating with manufacturers and technical partners to apply these technologies to new and existing vaccines. We have already transferred stabilization know-how to two manufacturers of childhood vaccines, and we have placed the freeze-protection technology in the public domain for free use by manufacturers.

PATH’s work is helping to give vaccine producers access to a broad range of stabilization technologies. Ultimately, this work will help ensure that children even in the most remote areas in developing countries are fully protected against common childhood diseases.

Photo: Umit Kartoglu.