Vaccinating Children Beyond the "Cold Chain:" Extending the Heat Stability of Vaccines

Yann Libessart/MSF


More than 22 million children worldwide did not complete basic childhood vaccinations in 2012, and an estimated 1.5 million children aged under five die every year from vaccine-preventable diseases.

Shipping and storing vaccines in a “cold chain” in the tropical heat of many resource-limited countries—whereby the vaccine is kept at temperatures between 2°C to 8°C from the point of manufacture until reaching the recipient—is a tremendous challenge and a major cause of poor immunization coverage rates. Ministries of Health and organizations such as Doctors Without Borders/Médecins Sans Frontières (MSF), which carry out vaccination in developing countries, struggle with the immense task of keeping vaccines within the recommended temperatures in contexts where infrastructure is weak and electricity supply and refrigeration unstable.

Growing evidence shows that some vaccines can be safely kept outside the cold chain for certain periods of time. This more flexible use of the cold chain is called the “controlled temperature chain” (CTC) or a “flexible cold chain.” This approach has considerable potential benefits, including cost savings, preventing vaccine damage caused by accidental freezing, and, most importantly, making it easier to reach children living in remote places who would otherwise remain unvaccinated. However, very few vaccine manufacturers have released information on, or further studied, the stability of their vaccines outside the typical recommendation of keeping vaccines at between 2 to 8°C. This is in part because there is little to no need for a more flexible cold chain in wealthy countries, where refrigeration is unproblematic, and therefore there is little incentive for companies to pursue this matter. It is crucial that manufacturers, regulators and national immunization programs work towards evaluating and approving the use of vaccines in a CTC where possible.

In many places, you can often arrive at a health center—a place that should be buzzing with children—to find it is totally empty, no staff or anything. You understand why when you see that the fridge to store the vaccines is broken and no child has been vaccinated in months.

Dina Hovland
Sudanese refugees began streaming across the border into South Sudan in June 2011 when conflict erupted between the Khartoum government and the rebels of the Sudan People’s Liberation Movement-North (SPLM-N) in Sudan’s South Kordofan State. At the height of the crisis in Yida camp last summer, high mortality rates were reported among young children admitted to MSF’s hospital with respiratory tract infections, such as pneumonia, one of the leading causes of death. MSF determined that vaccinating with the pneumococcal conjugate vaccine (PCV) could result in a substantial mortality reduction in Yida. MSF has been working since September 2012 to procure PCV but faced significant delays due to lengthy negotiations and international legal procurement constraints. MSF was eventually able to obtain the vaccine from GSK at a reduced price, but delays have now pushed the planned vaccination into the logistically challenging rainy season. The objective is to immunize approximately 5,000 children under the age of 2 against several pathogens, including haemophilus influenza type B and pneumococcus. This is the first time that PCV is being used in South Sudan and one of the first vaccines to be implemented in compliance with the new WHO emergency vaccination recommendations.
Yann Libessart/MSF