TechNet-21 - Forum

This forum provides a place for members to ask questions, share experiences, coordinate activities, and discuss recent developments in immunization.
  1. Joel Nana Boateng
  2. Supply chain and logistics
  3. Wednesday, 24 February 2021

How far is stacking in vaccine refrigerators recommended and are there specific SOPs to guide in the event where we have to stack vaccines, because of high volumes?

Has stacking a significant implication on the potency of the vaccine with respect to the temperature distribution in the refrigerator?


Dan Brigden Accepted Answer

Hi Joel, this is a good question. Regarding your first point, I can't find any SOPs or other guidance specifically around stacking; however there are some related resources that you might be interested in. 


EVM Standard operating procedure (SOP) E6-06.1 “Storing vaccines and water packs in refrigerators and freezers”

There are some interesting diagrams, such as this one for storing vaccine in a front-opening refrigerator.


Two other resources may also be relevant.


Training for mid-level managers (MLM) 

Module 1. Cold chain, vaccines and safe-injection equipment management

"Make sure that vaccines, diluents and ice packs are loaded according to existing national guidelines." 
"Application of EEFO".


Immunization Academy video

Arranging Vaccines Inside Any Refrigerator

2 cms is recommended as the minimum distance between stacks.


Regarding your second question around whether the temperature distribution in the refrigerator can be affected by stacking vaccines, and therefore affect vaccine potency, this is a somewhat tricky issue. In principle, stacking in the fridge shouldn’t be a problem thermodynamically because the volume of a fridge is too small to permit the creation of micro-climates within the vaccine storage compartment.

However, if the stacking is such that the thermostat sensor gets covered/blocked by secondary packaging, then there might be an issue with the fridge’s temperature control, mostly caused by a compressor overdrive, leading to freezing. This will of course depend on the make/mode and placement of the thermostat sensor and is a very unlikely scenario. If there is any doubt, a LogTag or similar logger could be placed in a warm part of the refrigerator near the top or a cold part near the bottom and the maximum/minimum values checked on a dailiy basis.

Over-stacking may be more of a vaccine management problem. For example, can a health worker ensure the EEFO policy in a fully loaded fridge?

  1. more than a month ago
  2. Supply chain and logistics
  3. # 1
DATTA NALLE Accepted Answer

Most of the research references clealy indicates that the covid vaccine will be effective ultra-low temperature freezer between -80ºC to -60ºC (-112ºF to -76ºF).

  1. more than a month ago
  2. Supply chain and logistics
  3. # 2

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