Protecting lifesaving vaccine from freezing or heat damage

Health worker carrying coolers full of vaccines on his bicycle.

Extreme temperatures and challenging terrain can get in the way of delivering vaccines to children in remote areas. Photo: M. Dorgabekova.

With a soft thump, a factory worker loads a box of vaccines into a delivery truck. It’s a simple beginning to an arduous journey.

Over the next several weeks, the box will travel across oceans, continents, and national borders. It will be stacked onto a plane, loaded onto another truck, strapped to the back of a bicycle, or even carried on foot. If all goes as planned, it will eventually reach a remote clinic, bringing lifesaving protection to dozens of waiting families.

But the trip is long. What if the vaccines are damaged along the way?

At PATH, we research, develop, and promote innovative ways to safely and efficiently move vaccines and other essential medicines from the manufacturer to those who need them. Doing so requires a wide range of technologies, systems, and services commonly called a supply chain. Protecting temperature-sensitive products from harmful conditions is a key part of this work.

Making every link count

Many vaccines, for example, lose their effectiveness if they’re exposed to extreme heat or freezing conditions. Making sure they stay at the right temperatures at every step of a journey requires a global network of equipment and services called a “cold chain.” In fact, cold chain efforts are so important to the vaccine supply chain that the terms are sometimes used interchangeably.

Strong cold chains are vital for immunization programs. They can also be extremely challenging to maintain, especially in low-resource settings with unreliable electricity, poorly maintained equipment, and long distances between facilities. As a result, health workers are sometimes forced to discard vaccines that they suspect have been exposed to extreme temperatures. Worse, they may inadvertently administer damaged vaccines, leaving people vulnerable to disease.

PATH improves cold chains by developing and advancing innovative technologies with partners—and by fostering the advocacy, education, and consensus necessary to make supply chains a global priority. We also investigate methods to make the vaccines themselves less susceptible to damage from extreme temperatures.

Technologies to protect vaccines

PATH collaborates with partners from the public and private sectors to advance technologies that help countries monitor, transport, and store vaccines. These include:

  • The vaccine vial monitor (VVM), a small label that adheres to a vaccine vial and changes color over time to indicate whether the vaccine has been exposed to too much heat. Today, immunization programs around the world rely on VVMs to tell whether vaccines have been damaged.
  • The development and adoption of refrigeration and temperature-monitoring technologies. Examples include simple modifications that can make vaccine carriers and cold boxes less likely to expose contents to freezing, and solar-powered refrigerators that reduce reliance on electricity.
  • Research on the value and feasibility of methods to improve the thermostability of vaccines—that is, to make them less sensitive to heat and cold. As new techniques are developed, we work with vaccine manufacturers to apply them to vaccines.

Better systems, better health

Improving the vaccine supply chain is an effort that requires a coordinated global response. Together with partners, PATH works to stimulate innovation, demonstrate effective approaches, and align efforts.

For example, from 2007 to 2012, Project Optimize, a collaborative effort between PATH and the World Health Organization, brought global stakeholders together around common supply chain issues and challenges. Over the course of the project, we drew new attention to supply chains, built shared consensus around sustainable technical and strategic solutions, and laid the groundwork for continued improvement.

A broad approach

PATH’s supply and cold chain activities are good examples of the multifaceted approach we take to all global health problems. From advancing technologies to fostering awareness, urgency, and consensus, 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 never get in the way of a child’s chance to receive lifesaving vaccines.