Providers participating in any of California’s vaccination programs agree to use devices that comply with California VFC Program requirements. Continuous temperature monitoring is an essential component of each clinic’s vaccine management plan, but data logger reliability is a critical factor that helps to ensure vaccine viability.
What Are Data Loggers?
Digital data loggers (also called “continuous temperature monitoring devices” or “data loggers”) continuously read and record temperatures to provide an accurate report of vaccine temperatures over time. Data loggers
- monitor vaccine temperatures continuously—even when the practice is closed,
- may have alert capabilities to notify clinic staff of temperature excursions during non-business hours,
- determine how long vaccines have been exposed to out-of-range temperatures,
- prevent unnecessary vaccine losses when excursion time frames cannot be precisely determined, and
- save recorded temperature data as an electronic file for analysis of temperature trends over time.
Primary & Backup Devices
Participating providers must use a VFC-compliant data logger in every refrigerator and freezer storing publicly supplied vaccines. Practices must also have at least one battery-operated backup data logger to use when a primary device is being calibrated, during emergency vaccine transport, or if a primary device fails. Depending on the size of the practice, additional data loggers may be needed.
Data Logger Specifications
Participating providers agree to comply with device specifications provided by the California VFC Program. Data loggers must meet these requirements:
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Feature
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Description
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Accuracy
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+/-1.0°F (+/-0.5°C)
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Logging interval
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Programmable (at least every 30 minutes)
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Memory storage
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4000 readings or more
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Buffered temperature probe
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- Only use the buffered probe bundled with the device
- Detachable from unit, or permanently embedded in a buffer as long as the temperature monitoring system can be calibrated
- Immersed in a vial filled with thermal buffer material, including liquid up to 60 mL (e.g., glycol, ethanol, or glycerin), loose media (e.g., sand or glass beads), or a solid block of material (e.g., Teflon® or aluminum)
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Digital display
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- Active external display
- Must include current, MIN, and MAX temperatures
- Must be in close proximity to the vaccine storage units and temperature logs
- Low-battery indicator
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Alarm capabilities
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- Programmable
- Visual or audible alarm to signal out-of-range temperatures
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Reports
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- Must generate a summary report of recorded temperatures that include minimum and maximum temperatures
- Total time out of range (if any), and alarm settings
- Generates PDF or secure PDF reports
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Also, data loggers must meet current calibration and recalibration requirements.
Unacceptable Temperature Monitoring Devices
Any device that does not meet California VFC Program requirements is prohibited, including but not limited to
- thermometers (e.g., round dial thermometers, fluid-filled and/or min-max bar thermometers, household-use and kitchen thermometers, infrared temperature guns, alcohol or mercury thermometers, and bi-metal stem thermometers);
- chart recorders, which are units that plot temperatures on printed graphs;
- data loggers that do not have probes immersed in a vial filled with liquid, loose media, or a solid block of material; and
- new devices that only generate CSV data files or Excel spreadsheets.
Purchasing Considerations
There is a wide range of data loggers on the market that come with features that may better suit your needs than just the basic models. Data loggers might be simple, stand-alone devices or more sophisticated with enhanced functions such as cloud-based technology and remote access to temperature readings.
The California VFC Program does not endorse or promote specific temperature monitoring devices. Use the VFC Data Logger Feature Comparison Guide as you research devices to meet practice needs.
2020 update: New devices must be able to generate a summary report of recorded temperature data since the device was last reset; summary reports must include minimum and maximum temperatures, total time out of range (if any), and alarm settings. Devices that only generate CSV data files or Excel spreadsheets are not acceptable.
See also Questions to Ask Vendors about Digital Data Loggers.
When You're Ready to Purchase
Many companies sell data loggers, but specialized medical equipment suppliers and manufacturers’ distributors are generally more knowledgeable and offer the best information about them.
Consider using the VFC Digital Data Logger Pre-Purchase Worksheet to select the device for purchase.
Here are some product vendors and/or distributors. This list is not exhaustive and includes only common search results: Control Solutions, Inc, Dickson, Onset, and Traceable products.
Certificates of Calibration
Because monitoring devices experience a “drift” over time that affects their accuracy, all data loggers must be certified for accuracy every two to three years or according to the manufacturer’s suggested timeline. Every data logger must have a valid and current certificate of calibration on file. Calibrate primary and backup devices on different schedules to ensure all refrigerators and freezers are always equipped with compliant data loggers.
Preparation for Recertification
Two to three months in advance of annual recertification, clinics are strongly encouraged to verify that all data loggers are calibrated, certificates of calibration are current, and expiration dates are documented in the clinic’s vaccine management plan.
Additional Resources
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