Cold Chain’s Un-Interrupted Vaccine Distribution

Published by Ariel Arcebido on

vaccine temperature monitoring and cold chain

Improve Cold Chain Visibility

Problems with cold chain distribution and storage around the world have led to vaccines being rendered useless for immunization sessions. Poorly coordinated and obsolete cold chain technology has made transporting medical products almost out of reach for patients badly in need. This has raised both public awareness and retailer demand for higher levels of food safety.

Epidemics occur after disasters. Health protocols are stretched to the limit as infrastructures are destroyed and access to clean water and sanitation facilities are cut off. For bigger disasters, the breakdown of healthcare systems compromises essential services such as vaccination programs. With that in mind, vaccination campaigns are essential to humanitarian operations.

The insufficiency of competent cold storage and lack of cold chain management produce high waste rates and poor immunization coverage. The WHO (2014) report in 2011, more than 2.8 million doses of vaccines were spoiled due to cold chain disruptions in five countries. Vaccines that are exposed to temperature excursions may not only lose their effectiveness but also prove deadly to the patients they are intended to protect.

An example is a recent incident that shows the importance of vaccine cold chains: in May 2017, 15 children died of toxicity from contaminated vaccines in Kapoeta in South Sudan. A joint WHO/UNICEF investigation showed that the vaccination team did not follow the cold chain protocols as stated in the Measles Supplementary Immunization Activities guidelines. The vaccines were stored in a building without refrigeration for four days. Not only that, as prices for vaccines are rising, the loss of large batches of vials due to defective cold chains increases the viability of the global vaccination effort.

To cope with these problems, different technologies have been tested to help solve some of the most pressing vaccine cold chain challenges (hereinafter cold chains). Just like any other humanitarian logistics problem, decision-makers need to plan a complex series of tasks along the supply chain, while dealing with changes in capacities and needs, as well as the slow reporting cycles. Cold chain decisions, however, are unique because the consequences are irreversible. If the vaccines cannot be kept within the prescribed temperatures, the cold chain is disrupted, and vaccines will turn from potential lifesavers into toxic liquids.

The Vulnerability Of Vaccines

Vaccines can only save lives if they remain cool. Most vaccines are viable for a temperature range of 2-8°C (35-46°F), which is their “safe range.” Although heat exposure must be avoided at all times mostly in the cold chain, freezing is also a problem with an astonishing 75-100% of vaccine chains. Vaccines with active ingredients will definitely spoil if frozen. With temperatures higher than 8°C (46°F); however, the effectiveness of a vaccine lessens, and may do harm if not cooled and handled accordingly.

Managing A Vaccine Campaign

A typical cold chain strategy has three stages, dedicated to planning, implementation, and evaluation respectively. The planning phase is all about the design of the vaccine campaign, including sourcing, network planning, and distribution, or inventory management policies. Given the long lead times for cooling equipment and vaccines which could be several weeks or months, these planning decisions can typically not be revised during the ensuing campaign. In the implementation stage, vaccines are transferred from national warehouses through a chain of the district and regional warehouses until they are distributed. The post-campaign stage is the evaluation with the purpose to inform advocacy, strategic planning, and training.

Throughout the cold chain stages, from the arrival at the airport to the last mile destination, vaccines must remain at a constant temperature range. This means that vaccines must be stored, packed, and transported under cold chain conditions. Cooling systems, however, are usually not the same in every transit point. While the cold chain equipment has the possibility of failure in some way while in the field, there are alternative options to keep the products in working order.

Cold chain equipment can be classified into active refrigeration systems and passive cooling devices. Even though the passive cooling solutions may seem basic, the cost for setting up the cold chain can come to almost 50 percent of the total expenditure.

Active systems include main and remote refrigerators. Main refrigerators are cooled by compressors that are powered by electricity. Remote refrigerators include two main subsets: absorption refrigerators powered by liquid petroleum or kerosene, and solar-powered adsorption refrigerators, which use either solar batteries or directly from the solar panels themselves. For active cooling systems, the reliable functioning of its machinery and its correct use is essential for keeping the products cool; they provide continuous operations and therefore do not require minute planning.

vaccine last mile delivery in Nepal

Passive cooling devices are cold boxes and vaccine carriers. Cold boxes are devices that have a capacity of 6-25 liters, this carried by motor vehicles, while vaccine carriers are smaller containers with 0.5-3.5 liters, and can be carried by hand or on bicycles or motorbikes. They are called passive because there is no active cooling mechanism. The cooling method used is by placing coolant packs containing change state solution which is usually plain water frozen into a solid form.

To avoid damage by freezing in passive cooling devices, more steps of “conditioning” are needed, taking the coolant packs out of the freezer long enough so that they begin melting before placing them in the device. Using gel packs used as an alternative, or other products with sufficient thermal mass to control the temperature like frozen meat. In the cold chain process where passive cooling is used, timing is crucial, and it can be compromised if there are delays.


In the reality, the cold chain process can be hindered by a variety of disruptions. The humanitarian cold chain needs to be such to support material and data flows. The movement of products requires physical capabilities in terms of infrastructure, storage, and resources such as transportation. Next, the data flows are used to support the coordination of the physical flows and decision making along with the cold chain processes.

Using the three-fold understanding of a cold chain when it comes to the physical movement of goods, informational flows, and decision making, the cold chain failures can be traced to any of these:

  • Lack the physical structures such as facilities, capacity, and goods leading to a disruption of the material process;
  • Information loss and the lack of ability to correct defective information;
  • Failure to make a decision, coordinate, or planning.

The infrastructure and capacity process is critical to the data information to the decision making that influences the physical capacities. Humanitarian technologies are being used to overcome the barriers in cold chain operations:

  • By improving local capacity to solve the infrastructure problems;
  •  By reducing uncertainties or information loss;
  •  By increasing flexibility to correct faulty decision making.

The following technologies have shown great potential and received critical attention in the humanitarian policy debate:

  • Solar panels and drones for the physical layer
  • Monitoring and tracking solutions
  • Information systems to provide the data flow

The functionality of these three technologies designed for vaccine cold chains is currently being applied (solar panels, information systems) or being tested (drones and monitoring, and tracking systems).

The Humanitarian Vaccine Cold Chain: Infrastructure And Capacity Facilities

Infrastructure disruptions include power failures or washed-out roads or bridges. Also, the telecommunication grid may be damaged and warehouses or sea and airports rendered useless by natural disasters. Equipment and transportation may not be able to deliver and lack spare parts, and energy or water systems inoperative due to power failures.

As these infrastructure and capacity disruptions occur with utmost certainty in disaster-affected areas, it is necessary that technological innovations are brought into operation to overcome these obstacles.

Two such technologies are currently being explored:

  •  Drones to overcome limited accessibility
  • Solar refrigerators to compensate for the lack of reliable power systems.

The Innovative Use Of Drones For Delivery

drone delivery of vaccines as part of the cold chain

When it comes to the distribution of the vaccines to remote areas, the last mile problem is always an obstacle due to damage or lack of infrastructure. Failure to reach its final destination can result in the decrease of accessibility to remote regions which can cause the resurgence of nearly eradicated viruses.

Despite the experimental state of the technology, proponents of cargo drones argue that the cargo drone is a “game-changer”. Drone technology can solve the last mile challenge and can overcome the problems of inaccessibility, efficiency, and punctuality in the cold chain with guaranteed delivery in minutes.

Technology futurists foresee that at the point of need, a health worker will contact the nearest district store with the prescriptions. The drone will then deliver what is needed, patients are treated, waste is eliminated and there is no speculating on the dosage. The potential use for drones will save money on local clinic inventory, and optimize healthcare capacity. Minimum inventory levels will reduce wastage from faulty, overstocked, or expired medication, lowering costs. Altogether, cargo drones will make systems responsive rather than predictive. This is essential for cold chains, where storage requires significant investments, and transportation has to be more efficient to ensure that vaccines remain cool.

From a cold chain’s view, the successful use of drones will depend on the availability of trained staff that oversees the drone system. On a more strategic level, with the efficient use of drones and the prospect of zero waste, a lean management strategy needs to be in place, in which warehouses and distribution centers have the needed inventory. This will require a shift of the cold chain strategy to meet the local demands to deliver in real-time. Otherwise, this strategy will only lead to an oversupply of inventories and wastage at the storage facilities.

Solar Refrigerators For Power Supply

solar panels to supply cold chain

Similar to cargo drones, solar refrigerators can also be a game-changer in the field of the cold chain strategy, and it will have both humanitarian and ecological impact once successful. For example, in April 2016, the ICRC installed solar panels at 32 healthcare clinics in the Gaza Strip to ensure that vaccines remain preserved in a power-deprived territory. As an alternative to the cold chain challenges, solar refrigerators were already in use in the early 1980s in the context of the Expanded Program on Immunization.

Solar power is a remote power technology, and most of the countries desperately needing vaccines are geographically compatible with solar cooling. In particular, the UN finds solar power as being beneficial to women and children, in ensuring their safety such as cooking stoves instead of open fires or for educational benefits by providing reading lights and basic healthcare.

The UNICEF approves of the use of solar refrigerators in a recent report, advocating for the replacement of traditional absorption refrigerators that are consuming kerosene or gas, due to problems to guarantee access to kerosene/gas, environmental aspects, and difficulty of maintaining temperature maintenance. In addition, there are no kerosene- or gas-driven refrigerators that are up to the minimum standards established by the WHO Performance, Quality, and Safety system.

From a cold-chain perspective, solar refrigerators enhance buffer and storage capacity in remote locations far from the power grid. Their use in the cold chain will depend on enabling local staff to work on this decentralized storage system. Making informed routing decisions, for instance, local staff needs to know if the solar refrigerator is up and ready and if its location can be accessed in time to preserve the vaccines, given the status of the transportation network. Such information needs to be always be updated and fed into a logistics planning system.


Humanitarian disasters often come with massive evacuation movements and resettlement in camps that are short of clean water and nutrition. Also, having poor sanitation and waste management. Disasters also compromise routine health services. These risks often target vulnerable people like children and pregnant or nursing women at risk. As such, vaccine immunizations are an important part of humanitarian operations to halt the downward spiral for the most vulnerable populations. Cold chains are essential for vaccine campaigns. The temperature of vaccines, which need to be kept within the prescribed temperature, poses a significant constraint on storage, handling, transportation, distribution, and management.

Thus the need to have an uninterrupted cold chain line to keep the temperature constant and to have a reliable delivery system to get those vaccines to the patients who really need them.

New technologies are constantly being researched to improve the cold chain strategy. Systems like the delivery of vaccines through drones, the use of solar refrigerators, or implementing tracking and monitoring systems may solve the cold chain management problem.

To make these innovations fully effective, several key problem areas need to be researched further in order to achieve a more responsive cold chain.

To do that, better clarity on the uncertainty, information, and irreversibility in the planning and implantation stage, is therefore essential to advance the effectiveness and efficiency of humanitarian vaccine cold chains.

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