Protecting lifesaving vaccine from freezing or heat damage

How does a mother in rural Indonesia get the vaccines she and her newborn need when the nearest health center is a boat ride away? How can a fragile vaccine be safely transported across waterways, countries, and continents to reach the Indonesian health center in the first place?

Maintaining the vaccine “cold chain” of proper refrigeration, from manufacturer to beneficiary, is vital for immunization programs—and extremely challenging, especially in low-resource settings. Most vaccines must be transported and stored within a very narrow temperature range. High temperatures, scarce resources, unreliable electricity, and long distances between health care facilities can break the chain. Overheating and accidental freezing alike can damage vaccine potency and lead to wasted vaccine that must be discarded or, worse, to children receiving vaccinations that won’t protect them from disease.

Overheating and accidental freezing alike can damage vaccine potency.

A weak cold chain limits how far a vaccine can be transported—and therefore how many people can access the lifesaving intervention. PATH develops technologies for effective refrigeration and temperature monitoring to strengthen the cold chain and help children and others get the vaccines they need. We also work with countries and international health partners to evaluate cold chains and develop training curricula for health workers to encourage best practices for cold chain management.

Innovations for temperature control, monitoring

Vaccines must be stored between 2°C and 8°C to prevent spoilage or freezing. But health care workers can’t always regulate storage temperatures or tell if a vaccine has been exposed to excessive heat or cold. PATH creates technologies that address both ends of the spectrum:

• The vaccine vial monitor, or VVM,—the world’s smartest sticker—is a small label that adheres to a vaccine vial and changes color to indicate if the vaccine has been exposed to too much heat. Today, developing-country immunization programs around the world rely on VVMs to tell if a vaccine has been damaged. VVMs improve outreach services to remote locations and reduce unnecessary wastage of vaccine.
• New refrigeration and temperature monitoring technologies help health clinics and facilities maintain their vaccines at safe temperatures. PATH is working with international partners to introduce into public health programs solar-powered refrigerators and refrigerators that prevent freezing temperatures.
• Techniques borrowed from nature and the food industry can stabilize vaccines to protect them from extreme temperatures. PATH is researching several methods to improve the thermostability of vaccines for common childhood illnesses such as measles and diphtheria. We’re working with vaccine manufacturers to apply stabilization techniques to new vaccines as they’re developed.

Policies and training for an effective cold chain

Immunization programs need proper tools for handling vaccines safely, and they need the know-how to effectively operate equipment and store vaccines.

• We use our cold-chain expertise to develop training and manuals on preventing vaccine damage in the cold chain. PATH helped the World Health Organization (WHO) draft a statement on how to prevent vaccine damage from freezing. We also assisted WHO to develop a protocol, now in use in many countries, for evaluating the risks of freezing in the cold chain.
• We work on a global level to implement proper cold-chain policies and in individual countries to improve the reach of vaccines to children in remote areas. For example, in China, Indonesia, and Vietnam, PATH has modeled strategies for taking the heat-tolerant hepatitis B vaccine out of the cold chain and storing it at room temperature to reach newborn babies who are born in rural homes far from health clinics.
• We also help countries access the tools they need to ensure that vaccines are stored safely now and into the future. In 2007 PATH launched a field assessment in Uganda of our new Cold Chain Equipment Management Tool. The software helps countries quickly and accurately project their future needs for refrigerators and other cold chain equipment, taking into account the age and status of their current inventory and new vaccines that will be introduced.

Our cold chain activities are a good example of the multifaceted approach we take to all global health problems. From advancing new health technologies to strengthening health systems—we’re working to ensure that effective vaccines are available even in the most remote areas of the world. Our goal is to make sure that temperature and geography don’t get in the way of a child’s chance to receive lifesaving vaccines.

Photo: M. Dorgabekova.