The Cold Complicated World of Freezing Vaccines

Published by Leo Almonte on

vaccine cold chain

Learning the Effects of Freezing on Vaccines from Various Studies and Research


Vaccines are sensitive to freezing. This article explores the cold and complicated work of freezing vaccines and the effect on efficacy. The critical importance of life-saving vaccines to healthcare is undebatable since it protects populations from disease and life-threatening conditions. Inside each vial is a medical concoction borne out of years of research, development and funding.

Yet, potent as they may be, vaccines are ultra-sensitive to temperature and light, and they lose their potency if storage environments deviate from required settings. The slightest change in temperature, or exposure to sunlight, can corrupt the medicinal compositions and render them useless.

The cold, complicated world of vaccine storage is so crucial that researchers all over the world have published dozens of studies to understand better, and manage the cold pharma chain. Transporting, storing, and distributing vaccines is challenging, especially in underdeveloped countries that lack logistics, good roads and utilities.

For instance, how could a health organization store volumes of vaccines in the middle of a desert without warehouses and reliable electricity? The safe transport of vaccines requires good roads and secured waterways travelling from Point A to Point B.

the vaccination supply chain

Amid harsh, unstable environmental conditions, vaccines need to be stored in specific constant temperatures to protect their potency. A critical backdrop looms over those challenges, since millions of people in a particular region depend on safe vaccine deliveries. A slight drop or rise of temperature in storage can easily jeopardize millions of dollars’ worth of vaccines and put an entire population at risk. 

Equally important to a physical pharma cold chain are qualified and well-trained personnel to handle vaccine storage and transport. Human error and oversight are also causes of vaccine wastage and impotence. Top to bottom training from managers, supervisors, carriers, drivers, health workers, medical doctors, to distributors, can at least reduce waste and ensure safe delivery.

Vaccines: Vials of Life

According to UNICEF, immunization is one of the most cost-effective public health interventions to date, averting an estimated 2 to 3 million deaths every year. As a direct result of vaccination, the world is closer than ever to eradicating polio, with only two remaining polio-endemic countries – Afghanistan and Pakistan.

influenza Vaccine Packge

Deaths from measles, a major child killer, declined by 73 percent worldwide between 2000 and 2018, preventing an estimated 23.2 million deaths. All but 12 countries have eliminated maternal and neonatal tetanus, a disease with a fatality rate of 70 to 100 percent among newborns.

World Health Organization and United Nations statistics on the coverage and benefits of immunization further demonstrate the critical role of cold chain and the correct way of preserving vaccines.

Effects of  Freezing to Vaccines

As an example case, the World Health Organization (WHO) recommends the following vaccines be stored and transported at 0–10 C:

  • Diptheria-tetanus  
  • Tetanus Toxoid (TT)
  • Hepatitis A and B,
  • Human Papillomavirus (HPV)
  • Meningitis C
  • Pneumococcal (PCV)
  • Cholera
  • Influenza
  • Haemophilus Influenza b (Hib)
  • Typhoid
  • Inactivated Poliovirus (IPV)

In 2015, researchers categorized nearly 60%  of the vaccines procured from the United Nations Children’s Fund Supply Division as freeze-sensitive. In the last ten years, the number of freeze-sensitive vaccines recommended by the World Health Organization increased by 50%.

vaccines and their temperature sensitivity

As biological products, vaccines become inactive over a period of time and must be stored in environments with narrow temperature ranges within the cold chain from manufacturing to distribution.  As previously mentioned, vaccines lose their potency when exposed to temperatures outside specified thermal ranges. 

Exposure to heat and light is also damaging to vaccines because they can cause vaccines to clump together and dilute their immunological properties.

Research on Cold Chain and Vaccine Freezing

 In 2007, a study revealed that 75%  to 100%  of vaccines in cold chains from 1985 to 2006  were exposed to freezing temperatures.  This research heightened awareness about the risk of vaccines being exposed to freezing temperatures in different countries.

Since then, researchers from different countries published various studies related to cold chain and the effects of freezing on vaccine integrity. These papers are available in PubMed, Popline, Embase, Biosis, and Google Scholar.

WHO and TechNet21 also published significant studies made between July 2006 to August 2015 on their websites which can be found using terms such as vaccine, temperature, thermostability, transport and freeze with the words “cold chain.”

To accurately analyze the vaccine freezing problem, researchers extracted information based on these inclusion criteria:

  • Year the study was published.
  • Year the study was conducted.
  • The country in which the study was conducted.
  • Type of temperature measuring equipment used
  • Duration vaccines were at or below the freeze threshold
  • The duration of temperature monitoring.
  • The frequency of temperature monitoring.
  • Unit of analysis
  • Study sample size (number of refrigerators or shipments)
  • Number of samples that registered freezing temperatures
  • Percentage of samples that registered freezing temperatures

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The Synthesis of Research Results

In 2017, a study done by Celina M. Hanson, Anupa M. George, Adama Sawadogo and  Benjamin Schreiber, entitled Is Freezing in the Vaccine Cold Chain an Ongoing Issue?  synthesized the results of various studies.

Among the significant results are:

  • Studies defined the threshold for low, cold or freezing temperatures at or below 2°C in 37 studies; however, three studies defined the threshold at or below 0°C and five studies did not specifically mention a low threshold. The lowest temperature reported was -21.3°C and the highest reported was 31.7°C. Complete temperature ranges were not available in 31 studies. Eighteen studies evaluated storage units or shipments that fell out of the recommended range of 2°C to 8°C, however, they did not specify exact temperatures or whether freezing occurred.
  • The sample size of the studies varied, ranging from one to 103 shipments or from three to 440 storage units. Storage units were described as walk-in-coolers, domestic refrigerators, ice-lined refrigerators, kerosene electric refrigerators, purpose-built refrigerators, bar-type refrigerators, cold boxes, vaccine carriers and study boxes. The transport segments and outreach sessions utilized vaccine carriers or cold boxes.
  • The analysis found that the percentage of shipments found below recommended temperatures in wealthier countries was 38% and 19.3% in lower-income countries. The percent of storage units where vaccines were exposed to temperatures below the recommended ranges were 33.3% in wealthier countries and 37.1% in lower-income countries. Three temperature monitoring studies during outreach sessions were found in lower-income countries and none were found from wealthier countries. The percent of vaccine exposure to temperatures below recommended ranges during outreach sessions was 18%.
  • Recommendations were included in all studies. The most commonly cited recommendation for countries was to conduct training sessions to improve supervision and the need for policies and guidelines.

From Information to Action

The publication of various studies on pharma cold chain and vaccine freezing had compelling effects in medical logistics. Governments have adapted more effective cold chain monitoring system to improve temperature data transfer.

For instance, Vietnam reduced the exposure of vaccines to temperatures below 0°C and identified temperature excursions through better monitoring systems. In Tunisia, vaccine exposure to temperatures below the required levels decreased by 12.1 percentage points and reduced freeze alarms to 40%. In India, the reorganization of their cold chain and training of health workers resulted in significant improvement in medical logistic management and operation.

Setting aside the highly technical data and scientific findings of the research, the improvement of cold chains relies on government response and action. Pharmaceutical companies should also offer support and incentives to help the cold chain maintain the vaccines’ integrity after manufacturing.


Continuous training and education among all personnel involved in cold chain tiers is one way of improving the system. Governments must also revise local guidelines and update their policies based on current industry trends and capabilities.

The success of effective vaccine storage affects countless lives in many countries, and all sectors involved in the cold chain must do everything in their power to ensure efficient cold pharma logistics.


In 2019, an estimated 14 million infants were still not reached by vaccination services from UNICEF

Is Freezing in the Vaccine Cold Chain an Ongoing Issue? by  Celina M. Hanson, Anupa M. George, Adama Sawadogo and  Benjamin Schreiber



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