Vaccine Transportation: Maintaining a Successful Cold Chain Without Reliable Electricity (Part 1)

What innovations have been developed to support cold chain logistics without relying on electrical access?

After reviewing some of the consequences caused by inadequate handling and fluctuations in vaccines’ temperature in the previous article, we will now explore the new practices and innovations that have been developed to overcome different challenges, related to the transportation, monitoring, and storing of heat sensitive vaccines where the access to electricity is limited.

Part I of this article will focus on solar-direct refrigeration technology and passive-cooled cold boxes; Part II will review the Energize the Chain project and new monitoring technologies.

In some regions of the developing world, having access to refrigeration equipment and electricity can be seen as a luxury. Energy poverty is a great problem affecting 3 billion people around the world who lack access to adequate electricity (almost half of the world’s population). Millions of children die every year from diseases that could have been easily prevented with vaccines that already exist, but remote rural areas might not have access to the technology and electricity required to keep those vaccines at controlled temperatures.

So therefore even when the supply of vaccines is readily available, and they get to rural villages in developing countries, the real challenge lies in keeping them from becoming inactive once they get there.

Coming next is a review of some of the most relevant technologies and innovations that so far have been developed to address the obstacle of developing countries without reliable access to electrical power. These technologies aim to maintain vaccines refrigerated within their temperature range without relying on electricity.

Solar-direct refrigeration technology

This technology evolved from electric refrigerators used in areas with insufficient power supply; electric refrigerators (a.k.a. absorption refrigerators) burn kerosene or liquid petroleum gas to keep a steady temperature range. Electric refrigerators have been around since the 80’s but have proven to be inefficient because of interruptions due to poor planning, fuel shortages, limited ice-making capacity, poor temperature control, and theft among other reasons. Despite their limitations in providing appropriate storage for vaccines, absorption refrigerators are still used in over 60% of vaccine storage locations.

The solar refrigerators that came soon after were first generation refrigerators that contained an industrial battery for storing solar energy, and even though some solar refrigeration projects have been successful for years, many suffered from battery system failures. If a battery replacement was not anticipated or there was no funding available, the entire system failed.

The second generation of solar refrigerators counts with battery-free solar direct-drive technology and doesn’t require any external batteries or backup generators; they use cool storage (an “ice battery”) that’s inside the refrigerator and is able to maintain acceptable temperatures for many days even at night or during cloudy and rainy weather. The WHO has pre-qualified six different solar direct-drive refrigerators since 2010.

Passive-cooled cold boxes

The most challenging part of cold chain operations, in terms of keeping temperatures steady, is probably what has been described as the “last mile”; which refers to the last stage of the delivery to its final destination. In countries like the U.S. the “last mile” usually involves trucks or vans and specific regulations, however, in developing countries the delivery of the last mile could be easily done by a person who rides a camel from town to town.

For over four decades, developing countries have heavily relied on containers/boxes with frozen water packs used for the “last mile” transportation of vaccines. According to the World Health Organization, these boxes can be carried by humans walking, bicycles, or motorbikes.

Regular cold boxes require ice packs or cold-water packs to keep vaccines cool; but if the temperature of the ice packs isn’t stable (0°C), there’s a great risk that vaccines will freeze; this has become a serious issue. The vaccines for tetanus toxoid, hepatitis B, pneumococcal conjugate, cholera, rotavirus, and human papillomavirus are among some of the most relevant freeze-sensitive vaccines.

New technologies have emerged with new designs for cold boxes. One of the most successful models of passive coolers for long-term vaccine storage without electricity has been the Nano-Q™. These boxes provide up to seven days of refrigeration at outside temperatures of 32°C before the ice needs to be replaced; it uses regular ice that’s available for purchase nearby from health centers and provides easy monitoring. These passive-cooled cold boxes were part of a program in Vietnam, which yield great results: no freezing temperatures were recorded over more than 65 months of cumulative data. “Users appreciated having vaccine storage that was independent from the electrical grid, as electrical cuts are common”.

Other models and designs of passive-cooled cold boxes have been designed, but their cold life varies between three to up to five days; the Nano-Q™ can keep vaccines refrigerated for the longest.

The second part of this article will look into other innovations and technologies being used to ensure the efficiency of cold chain logistics without reliable access to electricity.

When many outside factors, including efficient access to electricity, contributing to the struggle of maintaining the cold chain, the monitoring at every link of the process becomes critical and fundamental to achieving the desired results from using the vaccines.