Providers participating in any of California’s vaccine programs agree to use data loggers that comply with VFC Program requirements.
Benefits
Continuous and accurate temperature monitoring is essential for proper storage and handling. An accurate record of vaccine temperatures minimizes loss of vaccine potency and potential revaccination. Data loggers offer these features:
- continuously record vaccine temperatures—even when the practice is closed
- determine how long vaccines were exposed to out-of-range temperatures
- notify staff of temperature excursions so action can be taken to protect vaccines
- generate temperature data files that can be used to look for excursion trends
Purchasing Considerations
Providers may purchase any digital data logger that meets VFC specifications. The California VFC Program does not endorse or promote specific devices.
Providers must equip every refrigerator and freezer storing publicly supplied vaccines with a data logger and have at least one backup, battery-operated data logger. Depending on the size of the practice, additional data loggers may be needed. Data loggers must meet current calibration and recalibration requirements.
VFC Specifications
Data Loggers
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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 buffered probe bundled with device
- Detachable from unit, or permanently embedded in a buffer as long as device 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 summary report of recorded temperatures including minimum and maximum temperatures
- Total time out of range (if any) and alarm settings
- Generates PDF or secure PDF reports
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Unacceptable Temperature Monitoring Devices
- 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
- new devices that only generate CSV data files or Excel spreadsheets
Research Considerations
Data loggers might be simple, stand-alone devices or with enhanced cloud-based technology and remote access to temperature readings. Use the VFC Data Logger Feature Comparison Guide as you research devices to meet your location’s needs.
When You're Ready to Purchase
How to Calibrate Data Loggers
- Confirm data logger is VFC-compliant. Do not rely on device photo.
- Find a calibration laboratory that can provide a VFC-compliant Certificate of Calibration (PDF).
- Place backup data logger in storage unit while primary device is being tested, or vice versa.
- Ship device to the laboratory.
- When device is returned:
- Review certificate of calibration to confirm testing results. If certificate shows results of “fail” or “not in tolerance”, device must be replaced. Contact the laboratory if you are unclear about testing results.
- Keep certificates of calibration on file and make them available to Field Representatives upon request.
- Schedule a reminder for recalibration in advance of expiration dates of each device’s certificate of calibration.
Configuring Devices
Use these instructions (PDF) to configure primary and backup data loggers. Refer to your device’s product guide or video to learn how to use it. Call the vendor’s support number for all questions regarding setup and functionality.
Routine Maintenance
Devices experience a drift over time that affects accuracy and must be calibrated every two to three years or according to manufacturer-recommended timeline.
Normal Wear and Tear
Periodically inspect primary and backup data loggers.
- Routinely check cables and probes to verify they are not damaged.
- Replace batteries on a regular schedule.
- If a data logger is dropped, hit against the side of a storage unit or potentially damaged in any other way, verify its accuracy against another calibrated device.
When to Replace Devices
Purchase a new data logger if existing device or probe malfunctions, is damaged or if calibration testing indicates that the device is no longer accurate within +/-0.5° C (+/-1.0° F). A new device might be less expensive than calibration testing.
Preparation for Recertification
Two to three months in advance of annual recertification, locations are strongly encouraged to verify that all data loggers are calibrated, certificates of calibration are current and expiration dates are documented in your vaccine management plan.
Additional Resources
Videos:
