Vaccine and refrigerated medicine temperature

TL;DR: Vaccines and thermolabile medicines must be kept between 2 and 8 °C from the moment they leave the manufacturer until they are administered. Both heat and freezing can damage them without any visible sign. Surisa's adhesive indicators make it possible to monitor the refrigerator in real time (2–8 °C) and to leave a permanent record of exposure below 2 °C or above 8 °C during transport.

A thermolabile medicine is one that loses efficacy or degrades if it leaves its temperature range. That is the case for most vaccines, insulins, biological preparations and some diagnostic reagents. The set of conditions that keep that range during storage, transport and distribution is known as the cold chain.

The problem is that a break in the cold chain leaves no visible trace on the product. That is why a system is needed to warn you if the temperature left the range at any point.

Storage temperature: the 2 to 8 °C range

In international technical terminology, this is referred to as cold chain monitoring, vaccine storage temperature and temperature excursion (when the product leaves its range).

Situation	What happens	How it is detected
Between 2 and 8 °C	Correct range for most vaccines and refrigerated medicines	Refrigerator reading
Above 8 °C	Progressive loss of efficacy, depending on the exposure time	Time and temperature indicator
Below 2 °C or frozen	Many vaccines are irreversibly damaged by freezing	Temperature drop indicator

Every product states its storage conditions on its data sheet, and that is the reference that prevails. Some medicines that do not need refrigeration still have an upper limit, usually 25 or 30 °C.

Medicine refrigerators

The refrigerator is where a thermolabile medicine spends most of its time, in the pharmacy, the health center or the hospital. Good practice means:

• Using a dedicated medicine refrigerator, not a domestic one shared with food.
• Checking and recording the temperature at least once a day.
• Not placing medicines against the walls or the back, where there may be colder zones.
• Avoiding long and frequent door openings.
• Reviewing what happened overnight or over the weekend, when nobody is watching the refrigerator.

A reversible adhesive thermometer shows the temperature at that moment with no batteries or instruments. Surisa's LCD refrigerator thermometer covers 1 to 12 °C with a color code: blue below 2 °C, green between 2 and 5 °C, orange between 6 and 8 °C and red above that. Its points carry a coating that delays the color change, so that the reading when the door is opened reflects the temperature inside.

Transport of vaccines and refrigerated medicines

Transport is the most delicate stage of the cold chain: there are vehicle changes, waits at loading docks and boxes that are opened and closed. In the European Union, the Good Distribution Practice (GDP) guidelines require storage conditions to be maintained throughout transport and deviations to be detectable.

Refrigerated medicines are transported in vehicles with a refrigerated compartment, in insulated boxes with cold packs, and in packaging validated for a given period. Temperature is monitored with electronic data loggers and with adhesive indicators stuck to the box or to the product itself.

An irreversible indicator has a clear advantage: on opening the box, the recipient sees at a glance whether the goods went out of range, without downloading data or using any instrument.

Types of cold chain indicator

• Reversible: they show the current temperature. They are for day-to-day refrigerator checks. For example, the 2–8 °C cold chain indicator, which shows whether the temperature is correct, too cold or too warm.
• Time and temperature: they change color progressively when the product exceeds a temperature for a given time. For example, WarmMark at 8 °C, with points that activate at 2, 12 and 48 hours.
• Temperature drop: they change color permanently if the temperature falls below a threshold. For example, FreezeSafe, with thresholds of 0, 2 or 5 °C.
• Combined: they detect both deviations on a single label. Coldchain Complete XS activates below 2 °C (full change after 90 minutes) and above 8 °C (full change after 8 hours).

Adhesive indicators complement, but do not replace, temperature data loggers when the protocol calls for a continuous record with data.

Frequently asked questions about vaccine and medicine temperature

At what temperature are vaccines stored?

Most vaccines are stored between 2 and 8 °C, refrigerated and not frozen. Some specific vaccines require freezing at very low temperatures. The reference is always the data sheet of each vaccine, which states its range and whether or not it tolerates freezing.

What happens if a vaccine freezes?

Many vaccines, especially those containing aluminum adjuvants, are irreversibly damaged by freezing and lose efficacy, even though their appearance does not change. That is why it is so important to detect temperature drops below 2 °C, and not only rises.

How do I know whether the cold chain was broken during transport?

With a temperature data logger or with an irreversible indicator stuck to the box or the product. A combined indicator such as Coldchain Complete XS changes color if the temperature fell below 2 °C or exceeded 8 °C for long enough, and the change cannot be reversed.

Which thermometer should I put in a medicine refrigerator?

One that lets you read the current temperature and, if possible, know whether there were deviations while nobody was watching. An adhesive LCD thermometer from 1 to 12 °C gives the daily reading with a color code. To cover nights and weekends, it is combined with an irreversible temperature drop or time and temperature indicator.

How long can a vaccine be out of the refrigerator?

It depends on each vaccine: its stability outside 2–8 °C is determined by the manufacturer, and there is no general figure. After an out-of-range exposure, the right thing to do is to consult the data sheet or the manufacturer before using it. A time and temperature indicator helps establish how long it was exposed.