Probes, not guesses
Air temperature lies. A small bottle of glycol tells the truth. How a monitoring setup earns its place on the shelf.
Open any fridge door and the air inside changes within seconds. The vaccines hardly notice. That gap, between how fast air moves and how slowly product warms, is the whole reason good monitoring uses a buffered probe.
What "buffered" means
A buffered probe is suspended in a material such as glycol, glass beads, sand or Teflon, so its reading follows the product rather than every draught.1 The same CDC guidance lists what a proper device should have: an alarm for out-of-range readings, a low-battery indicator, and a display showing current, minimum and maximum temperatures.1 Put the display outside the unit, and anyone can read it without opening the door or disturbing the probe.2
A rhythm you can keep
Where a continuous digital logger is not available, check and record temperatures at least twice every working day, and keep those logs for at least three years.3 If a unit's readings never move at all, suspect the probe, not the fridge.2 Try the checklist below, then screenshot it for your staff room.
The daily five
0 of 5 doneWhen the alarm sounds
Stop and check before you act. Public health guidance for data loggers is blunt about it: an alarm means pause, look, and document.4 Quarantine affected stock, note what you saw, and follow your programme's rules before deciding to use or discard anything.
Buying a logger? Ask for the certificate
Ask for an ISO 17025 calibration certificate and check its expiry date, plus whether the alarm is both audible and visible.4 Those three questions belong in every tender specification you write. Our monitoring range is a good place to start.
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Ask Medix WhatsAppSources
- US CDC. Temperature monitoring equipment (Vaccine Storage and Handling). cdc.gov ↗
- PPP Magazine. CDC guidelines for temperature monitoring (June 2015). pppmag.com ↗
- Immunize.org. Ask the Experts: Temperature Monitoring & Controls (last reviewed 10 April 2026). www.immunize.org ↗
- Public health practice flyer. A step-by-step guide to selecting and using a data logger for vaccine inventory (Alabama Department of Public Health). www.alabamapublichealth.gov ↗
