Innovating Cold Chain Equipment Technologies for Vaccine Supply Chains

Published by Emeli Zuno on

cold chain technologies

The demand for highly-efficient cold chain equipment (CCE) has been steadily increasing since the early 2000s. As a result, momentum for stimulating the development of two new cold chain equipment categories– solar direct-drive refrigerators and passive-cooled cold boxes – has been generated. Its aim was to eliminate the top market barriers and encourage manufacturers to meet the performance, quality, and safety qualifications set by the World Health Organization.

Rising Demand
source: PATH/WHO

Delivering vaccines to all parts of the world is an intricate task because of their sensitivity to both heat and cold. Vaccines are extremely fragile. They must be protected from fluctuations in environmental conditions at every link in the cold chain and constantly stored within the recommended temperature range – from the time of manufacture until the point of vaccination.  If temperatures become too high or too low, the vaccines can lose its ability to protect against disease.  Once the vaccines lose their potency, they cannot be regained or restored; hence, there will be a big waste of effort, money, and other resources.

Back in 2008, Optimize, a collaboration between WHO and PATH, carried out a study on cold chain equipment to determine the suitable technologies needed in the vaccine cold chain for the future. Based on the study, Optimize established a plan to promote the development of new technologies in order to meet the requirements of vaccine programs in low and middle-income countries.

Challenges in Improving Cold Chains

  1. Inefficient delivery systems

In most low-income countries, the delivery systems for immunization supply chains have continued to stay inefficient due to remote locations of health centers, zero access to electricity, and challenging contextual factors that have limited the manufacturers’ capability to meet the WHO prequalification.  To achieve the prequalification, manufacturers must submit product record files and third-party test results to the Performance, Quality, and Safety (PQS) program at WHO, showing their compliance with the issued specifications and test verification protocols designed for that particular type of equipment (e.g., refrigerators or cold boxes). 

This prequalification process poses a great challenge to most chain inventories, as they do not have the right systems needed for routine data collection, which limits the presence of accountability structures and prevents precise and consistent inventory updates.

On the other hand, the existing system has been effective for preserving a market for vaccine refrigerators, cold boxes, and vaccines; but again, it gives manufacturers little incentive to invest in research and development of cold chain technologies that are not yet established.

2. Lack of latest technology or “optimal” equipment

Although we live in a technology-driven world, large quantities of outdated equipment have been hindering the performance of cold chains.  These earlier generation units often have weak temperature controls, shorter holdover times, while lacking freeze protection, which makes new vaccines more susceptible to risk and breakdown – limiting the effectiveness of cold chains. 

Vaccine damage due to disorganized regulation of temperature has been a known problem in several countries and is mostly caused by equipment failure.  This constitutes serious threats to national programs.  One example is Ethiopia.  In this country alone, a mere 1% increase in vaccine wastage due to inefficient temperature control would result in a financial loss of over eight million USD per year.

3. Inadequate temperature monitoring and maintenance systems

Cold chain inventory data shows that many countries are having a hard time in keeping the required storage temperatures for vaccines. Temperature monitoring studies (TMS) show that active cold chain equipment is often functioning improperly, with other major temperature control problems.  As unfortunate as it may sound, malfunctions are considered normal at the facility level, where the Clinton HIV/AIDS Initiative (CHAI) and partner-supported TMS have found that 10 – 46% of CCE are exposing vaccines to risks of freezing.

Functionality issues caused by old temperature monitoring and maintenance systems  are not just normal occurrences in the cold chain, but are also representative of lingering gaps in CCE management.  Based on CHAI and partner-supported TMS’s reports, in Nigeria, the average time to fix a fridge at the lower government unit level ranged from two months to two years.  Furthermore, temperature excursions (which are events where Time Temperature-Sensitive Pharmaceutical Products are exposed to temperatures outside the prescribed range) are being undetected and unresolved.  CHAI and partner-supported TMS listed an example of how this is evident at the facility level:

• 9 – 20% of CCE in study facilities keep the sub-zero condition for more than 24 hours

• 12 – 13% of CCE in study facilities keep the temperature higher than 8 °C (46.4 °F)  for more than five days

This suggests that the competence and availability of current and future technicians should be improved; and all needed spare parts should be secured and readily-accessible.

New Technology as the Key to Advancement

Powered with PQS program, Optimize paved a way for new cold chains to rise, while helping WHO identify new specifications for battery-free solar refrigerators as well as innovative vaccine carriers and cold boxes that can preserve longer cold life, store more vaccines; and prevent freezing.  The next step was to encourage manufacturers and convince them to design new products complying with WHO’s new specifications.

  1. Battery-Free Solar Refrigerators

Many health centers are located in areas with limited or zero access to electric power and are experiencing frequent or long-duration power outages which make grid-powered cooling systems not ideal for vaccine storage.  For years, these health centers considered refrigerators powered by gas or kerosene (called “absorption refrigerators) as their best option.  However, there are a number of drawbacks with this kind of device, including its high maintenance and supply cost, inefficient cooling method (which puts vaccines at risk of exposure to freezing temperatures), damage to the environment, and most of all, its disqualification from WHO standards.  Although it is possible for the United Nations Children Fund (UNICEF) to purchase these refrigerators under special requests, WHO, together with UNICEF, published guidelines stating that solar technology should be preferred over absorption devices.

Coolar vaccine refrigerator

As a response to this challenge, the first generation of solar refrigeration systems was introduced with a design that can store energy in batteries, to maintain refrigeration during the night and cloudy days.  A majority of reports, however, have been published regarding failures involving the battery systems.  This had posed a problem for low and middle-income countries because the solar battery-based refrigeration systems heavily relied on high-priced and imported batteries with a service life of three to five years – making their replacement another issue to resolve. 

In addition, the type of battery system that this kind of refrigerator requires makes the device itself more susceptible to failure.  Manufacturers have tried producing  alternatives but they have not been successful due to cost and limitations of battery life.

Image source: WHO

With these setbacks in mind, refrigerator manufacturers in the last decade have shifted traditional solar refrigerators to solar direct-drive refrigerators, which eliminate the demand for batteries.  This “direct-drive” technology utilizes the sun’s energy in order to freeze water and other phase change material, and then use the cooling from the “ice bank” to keep the refrigerators cold during the night and cloudy days (where the sun’s energy cannot be used).   Other major advantages over solar battery-based technology include simplified installation, fewer maintenance requirements, and lower costs of operation.

The new solar-power refrigeration systems have shown four key benefits for the vaccine cold chain:

  • Laboratory testing has confirmed its high level of efficiency on several vital parameters, most significantly temperature control.
  • The system’s sustainable feature and low cost of regular maintenance satisfy WHO PQS standards.
  • The lifetime expenses of implementing direct-drive solar systems remain lower than the absorption technology systems; and are progressively competitive with grid-powered systems.
  • The solar-powered systems are environmentally better than absorption refrigerators in the sense that they eliminate the need to burn fossil fuels (which is one of the major factors contributing to global warming).
  1. Cold boxes and vaccine carriers

A cold box is an insulated container designed to keep the vaccines and diluents in their prescribed temperature range while in-transit or during temporary storage.  Vaccine carriers, on the other hand, serve the same purpose as cold boxes, but they are smaller and more convenient to carry.

Depending on the model and surrounding temperature, cold boxes can be used in storing vaccines for a maximum of about four days, when electricity is not accessible, when the health facility refrigerator is not operating, or when a passive container is required while the refrigerator is being defrosted.  Sharing the same short cooling period with cold boxes, vaccine carriers used by health workers generally have a cold life of less than one day.  This causes a huge problem for small and remote health facilities that don’t have enough access to equipment maintenance and repair services needed to keep the vaccines at their right temperatures for many extended periods of time during transport and storage.

In early 2009, Optimize encouraged the cold chain industry to submit designs or finished products for new devices meeting the following requirements:

  • The designs or products must prevent vaccines from freezing inside the compartment. 
  • The vaccine capacity should follow the specific provisions:
  • A 3-liter portable vaccine carrier for outreach efforts with a 3-day cold life.
  • A 3-liter stationary cold box for small health facilities with a cold life of 30 days.
  • A 60-liter stationary cold box appropriate for larger health facilities with a cold life of 30 days.
A small and short-range cold box that has a vaccine storage capacity of 6 litres with cold life of up to 57.9 hours
Image source: UNICEF

These specifications stimulated the motivation of cold chain manufacturers to innovate and design products that could maintain a longer cold life, compared to traditional boxes available. If passive coolers are to serve as the main equipment in small health facilities, they would need to maintain temperatures for longer periods of time.

During attempts to reach the 30-day cold life goal, technical challenges. Consequently, Optimize indicated that devices with cold life of at least 7 days would still be considered.

Product and Design Evaluation

To provide a fair and accurate evaluation of product and design submissions, Optimize organized review panels consisting of international experts in vaccine and cold chain technologies. The panel members were initially screened for perceivable conflicts of interest. Each member signed a confidentiality agreement, and each agreed to safely dispose of the used materials after review.

To guarantee an objective review, Optimize staff removed all information showing the producing company’s name and background before each submission. They evaluated the products on how properly and efficiently they met the specifications. Reviewers also offered additional remarks on the adequacy of the devices, manufacturing suggestions, and ideas for deployment to remote health centers in developing and third-world countries.  The findings were discussed via teleconference.

Response from the CCE Industry

Four companies based in the United States and Europe have already submitted product descriptions, including illustrations, photographs, specifications, and internal test results as a response to the challenge imposed by WHO. For the cold box and vaccine carrier challenge, two manufacturers have submitted cold box record files. The small response for the cold boxes might be on account of significant technical challenges attaining long cold life goals, and an unsettled market for these devices. 

In the case of solar refrigerators, three out of four products met PQS requirements during laboratory analysis and were consequently prequalified by WHO. In addition, Optimize supported the onsite-testing of two of the products in Senegal and Vietnam. Both of these submissions performed well during laboratory testing. 

In Summary

The main objective of Optimize was to increase innovation in the cold chain technology field to meet the growing needs of developing and third-world countries. Optimize challenged the industry to produce more advanced battery-free solar refrigerator and passive cooling equipment that met their defined product requirements. 

This project encouraged manufacturers by supporting product testing to facilitate regulative approval, and onsite-testing to illustrate the practical use and publication of results. Ultimately, two manufacturers who had not produced cold chain equipment for the public health market in developing countries, found the courage and motivation to participate. One of them now has their vaccine refrigerator prequalified by WHO. The challenges extended by WHO resulted in the creation of three new battery-free solar refrigerators. Two additional devices from contending manufacturers were presented separately, and have been already acknowledged by PQS.

This demonstrates how efficient communication between countries and vaccine stakeholders is required to advance existing technologies in the cold chain industry. It takes massive effort for both health organizations and cold chain manufacturers to ensure that the best information about technologies is available. This is a crucial step in making the market ready for new technology implementations. It is apparent that by emphasizing the experience of early adopters, and by continuing to spread the results of field studies in multiple countries, building awareness and interest in new and improved CCE products can be achieved.


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