John Lloyd, Vaccine Supply Chain Consultant. 

In the final struggle to reach children in areas of difficult access, immunization managers will surely need to use vaccines to the limits of their temperature stability with the least logistic constraints.

A great tool that’s helping vaccines work even beyond the cold chain is the  vaccine vial monitor (VVM). The VVM is attached to each vial of most vaccines in use provides assurance to the health worker whether or not the vaccine is safe and potent to administer, even in the event of a cooling failure. The accuracy of each VVM type matched to vaccine products has been extensively verified and an agreement to start using them was reached between WHO, UNICEF, manufacturers, and regulators many years ago.


With a valid VVM reading, vaccine may be administered even if the icepacks melted some time ago. This means the immunisation manager can provide the maximum cold chain protection that is feasible in the circumstances, but will not be prevented from using the vaccine beyond the cold chain to the limits of the stability of the vaccine. This practice has already been in use throughout the Polio Eradication Initiative using oral polio vaccine, the least stable of all the vaccines in use.

A new strategy has been adopted, which takes advantage of the VVM tool. “Controlled temperature chain” or CTC was established nearly five years ago in response to calls for more flexibility in the vaccine supply chain. CTC is defined by WHO as a specific set of conditions allowing for a vaccine to be stored and transported outside of the traditional 2º to 8 ºC cold chain temperature. The CTC:

  • Allows for a single excursion, just prior to administration
  • Temperature in vaccine carrier must not exceed 40°C
  • Involves durations specified in the vaccine label, must reach at least 3 days

Vaccine products must be labelled and approved by national as well as WHO regulatory authorities for CTC use. To date only 2 vaccines have received this approval, and only one, MenAfriVac®, protecting against Meningitis A, has been used in a CTC protocol in multiple countries during campaigns.

Although it is a welcome achievement to have a vaccine authorised for use in single-vaccine campaigns, there is a programmatic need in the immediate future to be able to apply CTC protocol to the suite of EPI vaccines that are taken on outreach journeys to reach children who would not otherwise receive immunisations. Reaching the unreached is required in order to meet the ambitious coverage and equity goals of Gavi’s next strategic period. How can we accelerate the application of CTC to a wider set of vaccines to support these goals?

This is a question that TechNet Conference last week started to answer last week. Find out more from one of the panel discussions here.