With the approval and distribution of the Pfizer and Moderna COVID-19 vaccines, many clinics and pharmacies have begun their search for a solution to monitor vaccine temperature that meets the requirements of keeping the COVID-19 vaccines safe. According to the Center for Disease Control (CDC), the Moderna COVID-19 vaccine should be stored long-term in a freezer at a temperature between -25°C and -15°C (-13°F and 5°F) or in a refrigerator at a temperature between 2°C and 8°C (36°F and 46°F) for up to 30 days before the vaccine vial seal is punctured.

The Pfizer-BioNTech COVID-19 vaccine has slightly stricter requirements, needing an ultra-low freezer with temperatures between -80°C and -60°C (-112°F and -76°F) for long-term storage. The vaccine can be stored in a refrigerator prior to mixing for only 5 days (or 120 hours) at a temperature between 2°C and 8°C (36°F and 46°F). The Johnson & Johnson (Janssen) COVID-19 vaccine should be stored at a refrigerator temperature between 2°C and 8°C (36°F and 46°F) until its expiration or beyond use date and should not be placed in a freezer for storage. Once the Janssen vaccine vial is punctured, it must be held between 2°C and 8°C for up to 6 hours OR at room temperature (up to 25°C / 77°F) for up to 2 hours.

With these stringent requirements, the CDC requires the use of a Temperature Monitoring Device (TMD) such as an electronic Digital Data Logger (DDL) to ensure that the temperature during the storage and handling of the COVID-19 vaccines is maintained properly and safely.

Key Features of a Temperature Data Logger

A key feature when using an electronic data logger is the ability to accurately determine the temperature of the vaccine. Unlike a simple min/max recording thermometer, a DDL can provide information on temperature excursions – how long the vaccine has been outside of the recommended temperature range. These devices typically allow recorded data to be downloaded to a computer or sent to a web-based cloud storage service to maintain historical records for up to 3 years – the CDC recommended archival period. They also allow the user to specify how often a measurement is recorded, typically at least every 30 minutes or faster. Rather than simply recording temperature data, more advanced DDL’s can provide alarms, either local visual or audible alarms, or via email, SMS, or voice to provide immediate notification of temperature excursions or loss of power. The devices normally use some type of probe that is placed within the refrigerator or freezer compartment. To accurately reflect the actual temperature of the vaccine, the CDC recommends the use of a thermal buffer – glycol bottle, glass beads, or Teflon block – on the probe to dampen temperature fluctuations due to door openings, etc.

While the condensed CDC storage and handling guides do not address calibration, the CDC Storage and Handling Toolkit document, recently updated to include the COVID-19 vaccines, requires that the DDL used for temperature monitoring be calibrated with the National Institute of Standards and Technology (NIST) traceability. This is to ensure that the temperature recorded by the device is accurate to provide the best protection of the efficacy of the vaccines.

Furthermore, the CDC has published additional guidelines for the Moderna, Johnson & Johnson, and Pfizer vaccines. In the case of the Moderna vaccine and the Johnson & Johnson vaccine, it is preferred that the DDL provide a daily minimum and maximum temperature either on the display of the device or in the software. If this is not available, it is recommended that the recorded daily data be inspected to determine the minimum and maximum temperature.

The recommendations for the Pfizer vaccine are similar with the exception that the DDL be able to measure dry ice temperature -80° to -60°C for long-term storage. For both of these, they can be stored in a refrigerator between +2°C and +8°C for shorter periods of time prior to dispensing.

Vaccine Temperature Monitoring Solutions

So which digital data loggers available on the market are suitable to monitor the COVID-19 vaccines?  For small scale vaccine storage, there are two key kits:

EM500-PT100 can monitoring -200~50 Deg C range, and data will by LoRaWAN