Why Medical Grade Cold Storage Units are Better for Vaccine Storage

Vaccine storage requirements

Vaccines are expensive and require storage in purpose-built equipment to maintain efficacy. Using medical-grade refrigerators and freezers will potentially save you money on wasted vaccine batches. Poorly stored vaccines will no longer be effective and require revaccination of patients when used. This guide will outline vaccine storage best practices.

Vaccines require:

● Consistent storage temperature of:

○ +2…8°C (+36…46°F) for refrigerated vaccines

○ -50…-15°C (-58…+5°F) for frozen vaccines
Tip: Adjust the thermostat to mid-point or the factory setting as this will help to sustain steady temperature

● Some vaccines need protection from light

Vaccine storage unit options

Purpose-built pharmaceutical grade unit
(CDC recommendation)
Domestic refrigeration unit
(not recommended for frozen vaccines)
Product features Benefit Product features Disadvantages
Computer controlled temperature Precise temperature adjustment. Manually controlled temperature Difficult to adjust temperature precisely. Water bottles must be used to assist with poor refrigeration performance.
Digital temperature sensor Precise temperature readings. No digital temperature reading or one not accurate enough for vaccine storage Precise digital temperature sensor must be installed separately.
Powerful fans Better air circulation, adjusts faster to chosen temperature. Weak fans Cold spots and temperature fluctuation.
Improved insulation Able to sustain even temperature. Low quality insulation Not capable of sustaining even storage temperature.
Perforated shelves, storage compartments Better air circulation, adjusts faster to chosen temperature. Solid glass shelves, plastic storage compartments Cold spots and temperature fluctuation.

Preferred features to have:

• a digital data logger
• self-closing doors
• digital alarm
• secure lock

Never use a domestic refrigeration unit with an internal freezer compartment to store vaccines. These units pose risks even for short term emergency storage.

When choosing a location for a refrigeration or freezer unit:

● Choose a well-ventilated room

● Optimal ambient temperatures of 20...25°C (68…77°F)

● Leave adequate space around the unit; At least 2 inches

● Place the unit on a level surface to allow the door to open and close smoothly

Temperature monitoring device:

● Must be placed within each vaccine storage unit, even if it is temporary.

● Digital data logger is recommended by CDC, which logs all temperature readings at set time span, not just displays current temperatures.

● Use a buffered temperature probe for most accurate vaccine temperature monitoring.

Digital Data Logger (DDL) benefits:

● Data can be downloaded to analyze

● Set data log frequency

Always keep a back-up calibrated temperature monitoring device. Keep the log data for at least 3 years or according to your local regulations.

Recommended digital data logger features according to CDC:

● Critical temperature alarm

● Low battery alarm

● Detachable probe (buffered with glycol, sand, glass, Teflon®)

● Recommended accuracy +/-0.5°C or +/- 1°F

● At least 30 min log interval

● Valid calibration certificate

CDC does NOT recommend using:

● Food thermometers

● Alcohol thermometers

● Mercury thermometers

● Infrared thermometers

● Chart recorders

● Any thermometers without a valid calibration certificate

Temperature monitoring device calibration

Temperature monitoring device calibration must be performed annually or every other year according to the manufacturer’s guidelines and after a mishandling or drop, which can affect the performance of the device.

Temperature monitoring device’s calibration certificate should indicate to one of more standards listed below:

● International Organization for Standardization (ISO) for testing and traceability

● International Electrotechnical Commission (IEC) 17025 for testing and traceability

● American Society for Testing and Materials (ASTM) Standard E2877 with tolerance class F or higher

● National Institute of Standards and Technology (NIST) standard maintenance

● International Laboratory Accreditation Cooperation (ILAC) Mutual Recognition Arrangement (MRA) signatory body laboratory accreditation

● Other acceptable accuracy validation methods

Data logger Calibration Certificate should have:

● Serial number

● Make and model

● Date of calibration

● Tolerance

● Confirmation on passing the calibration

Temperature excursion

When a temperature reading outside of the pre-set range has been detected by the data logger.

What to do:

● Train staff to notice it and take immediate action.

● Designate a vaccine coordinator and a substitute to take responsibility for the processes.

● Have a process in place for any occasion from the door being left open for a short period to a natural disaster scenario.

● Label the affected vaccines with “Do not use” and place them separately for the investigation.

Vaccine coordinator should:

● Record the time and out of range temperature for storage unit as well as ambient if possible

● How long the vaccines were affected

● List of materials in the unit at the time with product names and quantities

● Description on what happened

● Actions taken

● Vaccine manufacturer/supplier or your local immunization program’s comments

● Lessons learned

● Name of the vaccine coordinator

● Adjust the temperature to required

● Contact vaccine manufacturer/supplier or your local immunization program for guidance

Refrigeration unit maintenance

Continuous maintenance is very important to prevent losing the potency of the vaccines but also to achieve maximum efficiency. When preparing for or performing maintenance don't leave the vaccines in the unit that you suspect is not functioning as intended.

● Ensure a regular defrost schedule is in place. As soon as the evaporator coil shows signs of freezing up or frost forms around the seals, it is time to start defrosting.

● Check door seals for tight closing and door hinges for intended functioning.

● Clean, disinfect and dry internal surfaces regularly to prevent bacteria growth.

● Make sure your back-up equipment is regularly serviced and ready to go.


1. Adjusting temperature setting. This might be required when the ambient temperature changes from summer to winter and back again.

○ Plan seasonal adjustments on a day when the unit would not be heavily accessed.

○ Adjust the temperature according to your temperature log observations and do not open the door for half an hour prior adjustment.

○ Check after half an hour to decide if further adjustments are necessary.

○ Check the accuracy of your monitoring device with the calibrated back-up temperature monitoring device.

○ If you still need to adjust the temperature, read the refrigeration unit’s manufacturer’s manual for instructions. Medical refrigeration units allow for very accurate digital adjustments, but when using a domestic refrigerator unit make a slight adjustment at a time followed by an hour of settling time before checking the temperature reading again.

○ Allow the unit to settle for 30-60 min without opening the door before checking the temperature reading again.

○ Observe the settling time. If it takes too long for the temperature to settle, add more water bottles inside the unit to help stabilize it. Ideally, the unit should stabilize within 30 min.

○ Keep adjusting and checking until you achieve 5°C (40°F) for the refrigerator or between -50…-15°C (-58…+5°F) for the freezer.

2. Recurring alarms

● Do not ignore the alarms and do your best to investigate the cause

● Perform basic checks: cleanliness of seals and coils, clearance around the unit, correct thermostat placement. Check the temperature with the calibrated back-up temperature probe

● If the alarm keeps going off and/or temperature is out of range, move the vaccines into a back-up unit.

● Contact the unit manufacturer or your servicing team

●Consistent storage temperature of:

○ +2…8°C (+36…46°F) for refrigerated vaccines

○ -50…-15°C (-58…+5°F) for frozen vaccines

Tip: Adjust the thermostat to mid-point or the factory setting as this will help to sustain steady temperature

● Some vaccines need protection from light

Your laboratory deserves a refrigerator or freezer that meets all of your requirements. Shop from pharmaceutical refrigerator suppliers who make every penny worth it by visiting K2 Scientific today. We have the specifications and features you need to protect your materials, keep an organized inventory, and make your lab as productive and cost-effective as possible.