A vaccine fridge log needs more than the value read at that moment, because an overnight power cut is invisible in the morning: the unit has returned to normal by then. So the log records the highest and lowest temperature seen since the last reading. The CDC toolkit asks for this at the start of every workday; the refrigerator compartment is held at 2-8 °C.
- date, time and person reading
- highest, lowest and current value
- target range, printed in the header
- on an excursion: action taken, state of the vaccines and person notified
- on a power cut: date, duration and whether the door was opened
The lowest-value line matters as much as the highest: the CDC says a single exposure to 0 °C or colder can destroy potency, and an inactivated vaccine may not look frozen even when it has been.
On an excursion the vaccines are marked "do not use", held in a backup space that keeps 2-8 °C until a decision is made, and the vaccine lead is told; the lead decides on use or disposal from the product information. The CDC toolkit recommends the same order.
