Cold Chain Protocol - Vaccines and Biologics

Appendix 2: Defrosting a Refrigerator/Freezer

Frost-free freezers do not need to be manually defrosted. They have regular defrosting cycles three or four times a day when the freezer temperature increases and melts the ice automatically.

For freezers in non-frost free refrigerators:

  1. Remove all products from both compartments of the unit and place them into alternate storage unit(s) in accordance with written protocols.
  2. Turn off the power and unplug the unit.
  3. Remove all frozen packs from the freezer (keep frozen, if possible).
  4. Keeping the freezer door open, allow all the frost to melt.
  5. Loose ice can be removed by hand; no sharp tools or sharp instruments should be used to remove the ice.
  6. A container of warm water (not greater than +50°C) inside the compartment can reduce defrosting time.
  7. Once the frost has melted completely, clean thoroughly and wipe the unit dry. (This is also a good time to clean the refrigerator compartment).
  8. Connect the power and ensure that the thermostat is turned to an appropriately cold setting.
  9. Wait for each compartment of the unit to stabilize at the proper temperature range.
  10. Monitor and record the temperature every half hour for the next few hours until stable temperatures between +2.0 and +8.0°C have been reached in the refrigerator.
  11. Vaccines and biologics that require to be stored frozen should be in a freezer that is maintained at -15°C or colder.
  12. Re-stock each compartment with the product.
  13. Continue to monitor and record the temperature every half-hour for the next few hours.
  14. If defrosting is necessary once a month or more frequently, the door may not be sealing properly, the door may have been opened too frequently, or there may be other mechanical problems with the freezer. Consult a technician and monitor temperatures carefully.

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