What is CDC’s policy regarding the use of certified thermometers and the expectation in terms of frequency of re-calibrating thermometers?
The VFC Site Visit Questionnaire requires a practice to have one certified thermometer per refrigerator or freezer compartment and requires that this thermometer be used for recording temperatures If there is not a certified thermometer at the time of the VFC site visit in any or all of the vaccine storage units, then corrective action must be taken by the office to correct the situation, and the corrective action steps must be monitored by the grantee.
In the Vaccine Storage and Handling Toolkit, CDC recommends the use of refrigerator and freezer thermometers that have been individually certified against an ASTM or NIST standard. Additional information about thermometers is available in the Vaccine Storage and Handling Toolkit at http://www2d.cdc.gov/nip/vsh/ToolkitWeb/splash.html
Manufacturer specifications should be followed regarding recalibration, or recertification of thermometers. The manufacturer-specified frequency of recalibration varies by make and model, with recalibration every 1-2 years being typical. This should be considered as part of the overall cost when purchasing thermometers.
Graphing thermometers with moving parts and frequent pen/paper changes are likely to become less accurate with time. Comply with the manufacturer’s recalibration schedule. Digital thermometers may also become less accurate with time; however, these are relatively inexpensive, and may be less expensive to replace than to recalibrate. Bottle-type thermometers, which have no mechanical or electronic parts, are most likely to remain accurate for extended periods, and may be less expensive to replace than to recalibrate. However, bottle-type thermometers may be rendered inaccurate if the liquid column separates.
Grantees must set their own policies regarding which types of thermometers are acceptable and their recalibration requirements. Recalibration and recertification requirements should take into account manufacturer specifications and guidelines.
When a grantee checks the accuracy of thermometers at site visits, the following should be considered:
- The frequency of site visits. If a provider is visited only once in four years, it may be some time before an inaccurate thermometer is identified. This can also make evaluation of past temperature logs difficult in the event that temperatures fall outside the recommended ranges.
- The recertification of reviewer thermometers. If these will be used as standards for comparison, they should be recertified according to the manufacturer’s recommended schedule.
- The relative accuracy of thermometers. Nearly all thermometers will have some variance in accuracy (generally +/- one degree). The grantee should define the acceptable variance before recalibration or replacement is required.
