Vaccine Transportation Series: How Does the Cold Chain Affect the Potency of Vaccines?

The importance of the cold chain in developing countries facing limitations for the storage, transportation, and monitoring of vaccines caused by limited or unreliable access to electricity.

Some of the most important vaccines in the world are heat-sensitive, thus requiring custom transportation and storage to ensure their effectiveness. The process of transporting these products has been described as the cold chain, which involves sophisticated technologies such as refrigeration systems that prevent vaccines from losing their integrity. In this series we will explore the challenges that are faced by regions in developing countries where the access to electricity isn’t steady or reliable, and how they’ve managed to overcome their limitations.

The first piece of the series will serve as an introduction to the cold chain and its relevance; the second piece will explore real-life cases reflecting the most prominent challenges that countries have faced and the consequences of inadequately handling the vaccines; lastly, the third piece will cover the technologies and innovations that serve to facilitate the transportation and storage of heat-sensitive vaccines without relying on electrical power and the possibility of power failure.

Logistics are vital in determining the success of cold chains, which refers to the transportation of temperature sensitive products through thermal and refrigerated packaging methods. Logistics deals with to the management and detailed coordination of operations that allow the flow of goods from point of origin to point of consumption. Its primary operations focus on inventory, transportation, warehousing, packaging, and information management among others.

The cold chain aims to protect the integrity of products from the moment they leave the manufacturers until they reach the end users. The two major sectors concerned with cold chain logistics are the food & beverages and the bio-pharmaceutical industries. Several means of transportation are used in different stages of the cold chain, such as refrigerated trucks, refrigerated cargo ships, and air cargo. The main components that are usually involved in any given cold chain involves a process that begins with the manufacturer/supplier, followed by the transportation of the products to warehouses where the products are stored and then transported again until they reach the end customer.

For vaccines the dynamic of the cold chain involves more links (different steps of transporting or storing that vaccines go through). Most heat-sensitive vaccines must be kept between a range of 2 to 8 degrees Celsius at any and every given point throughout the links of the cold chain.

The preservation of an intact cold chain is imperative for the handling and transportation of temperature-sensitive drugs and vaccines, since temperature fluctuations are very likely to alter the effectiveness and outcomes of using these drugs. One of the biggest challenges consists in preventing them from freezing, since freezing affects the quality of vaccines. The World Health Organization (WHO, 2006) reported that the impact on the potency of vaccines each time they’re exposed to ambient temperatures is cumulative; which highlights the importance of a successful cold chain from beginning to end.

The global expenditures on the cold chain market from the bio-pharmaceutical industry rose from $5.1 billion in 2010 to $6.6 billion in 2011. The market will continue to grow as many more of the top global pharmaceutical products and vaccines require cold-chain handling, such as influenza vaccines, Hepatitis A & B, and varicella among others. The market is expected to grow on average 8% per year.

Maintaining a cold chain that doesn’t break at any point can become a very challenging quest when power outages are common. When there’s a lack of adequate temperature monitoring there’s no way to predict when the potency of vaccines has been compromised by previous breaks in the cold chain, causing undesirable and sometimes harmful results.

Monitoring and logging temperatures through the cold chain is key in the transportation of vaccines; however most monitoring devices are not immune to power outages and may stop reading and/or recording changes in temperature. Regions in developing countries where the access to electricity might be limited or not steady require special considerations that should be taken into account when choosing a monitoring device. SmartSense's system is capable of monitoring temperatures and it’s able to keep monitoring during power outages; it sends alerts via email, telephone, and text message when the temperature rises or falls out of range.

The next piece of the series will look into some of the situations where temperature has affected the efficiency of vaccines in developing countries.