Questions & Answers
Storage & Handling - Vaccine Storage
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Temperature Monitoring

  1. What type of thermometer is best for measuring temperatures in a vaccine storage unit?
    CDC recommends the use of a digital thermometer with a biosafe glycol-encased probe or a similar temperature buffered probe that will more closely approximate the measure of liquid temperature. A temperature buffer enables a thermometer probe to more closely match the temperature changes experienced by stored vaccine. Examples of temperature buffers are a probe inserted into a glycol-filled vial or one inserted into glass beads. To ensure validity of temperature measurements, only calibrated thermometers with a certificate of Traceability and Calibration should be used.

  2. Where within the vaccine storage unit should the thermometer be placed?
    In the refrigerator, it is important that the glycol-encased or similar temperature buffered probes be placed in close proximity to the vaccines being stored. Proper placement is very important since it helps the staff to most accurately identify the actual vaccine vial temperatures and to take appropriate corrective actions quickly if necessary.

  3. How often should temperatures be recorded for refrigerator and freezer compartments where vaccines are stored? And how should you document temperatures?
    Temperatures inside refrigerator and freezer compartments should be measured and recorded on a temperature log a minimum of at least twice a day (the room temperature should also be recorded on the log); once at the start of the day and a second time before the area is closed whether or not you have an alarm system installed. Army immunization areas must record the temperature a minimum of 4 times per day. Immediate action must be taken if the temperature is outside the recommended range for either compartment.

  4. Who should adjust the temperature of a vaccine storage unit?
    Only the primary or backup vaccine coordinator should adjust the temperature of a vaccine storage unit. Limiting access to the thermostat reduces the risk that the temperatures will be adjusted inappropriately. A warning sign should be posted on the storage unit that says, "Do not adjust refrigerator or freezer temperature controls. Notify (insert name) if adjustments are necessary".

  5. How often should I set the digital date logger to measure temperature?
    CDC's interim recommendation is to set the digital data logger to measure every 15 minutes. If you wish to set the data logger to measure temperature more frequently or if the manufacturer recommends a more frequent setting, that is acceptable. CDC is currently working with the National Institute of Standards and Technology (NIST) to evaluate the most efficient and effective settings for digital data logger temperature measurements.

  6. Do twice daily physical temperature checks need to occur if a data logger and/or alarm system is in place?
    Yes. CDC still recommends documenting twice daily temperature checks even with a continuous data logger and/or alarm system because twice daily checks will give you a better indication of any problem with your storage units function. Relying solely on alarms can lead to complacency and inappropriate temps may not be discovered in a timely manner (e.g., alarm battery failure). DoD has had many vaccine losses due to failure of alarm or call systems that were not being physically checked, these losses could have been avoided if someone was physically checking the temperatures.

  7. How long should temperature logs be maintained?
    Temperature logs should be kept for 3 years or per service/local policy. Archived temperature logs can show how well the vaccine storage unit is working overtime and can be used to determine when a unit may need adjustment, maintenance, or replacement, such as when temperatures are consistently at the limit or sometimes beyond the limit of the recommended temperature range.

  8. Should I have a digital data logger along with a thermometer in the vaccine storage unit?
    Yes. CDC's interim guidance suggests the use of digital data loggers with detachable probes that allow the reading of temperatures without opening the door and record & store temperature information at frequent programmable intervals for 24 hour temperature monitoring rather than non-continuous temperature monitoring.