Proper storage of immunobiological drugs is a critical stage in the supply chain of medical devices, directly affecting their effectiveness and safety. Violation of the temperature regime or incorrect placement of packages inside the refrigeration equipment chamber can lead to irreversible loss of the properties of the drug, which makes it unsuitable for use.
In this article we will analyze in detail the principles of organizing the space inside the refrigerator, the necessary temperature conditions for various groups of vaccines and typical mistakes that are made when storing them. Compliance with these rules is not just a bureaucratic requirement, but a guarantee that vaccination will be successful.
Temperature conditions must be maintained at all times, regardless of the frequency of opening the door. Even a short-term increase or decrease in temperature beyond acceptable values can activate or, conversely, inactivate the components of the drug.
Principles of temperature zoning of the refrigeration chamber
The internal space of any household or professional refrigerator is heterogeneous in temperature characteristics. Cold air, being heavier than warm air, sinks down and also circulates more intensely near the walls and rear panel where the evaporator is located. Therefore zonal distribution drugs are the first step to their safety.
The upper shelves are usually the warmest, as warm air rises when the door is opened. The lower shelves and the area at the back wall, on the contrary, can be areas at risk of freezing. That is why placement of vaccines requires strict discipline and understanding of the physics of processes.
The central part of the shelves is considered the most stable zone. Here the temperature fluctuates least during short-term access to the contents. It is important to avoid placing drugs directly against the walls, unless these are specialized trays for refrigerant.
Understanding these zones allows you to minimize risks. If you store drugs in a regular household refrigerator, be sure to carry out preliminary temperature mapping using thermometers placed at different points in the chamber.
Layout patterns: shelves, door and freezer
The most common mistake is storing vaccines on the refrigerator door. Door shelves experience the most significant temperature fluctuations every time the refrigerator is opened. In addition, in some models, the temperature at the door can drop below zero, which is detrimental to liquid forms of drugs.
The freezer compartment is intended exclusively for storage refrigerants (cold accumulators) or specific vaccines that require deep freezing (for example, some forms of oral polio vaccine), if this is indicated in the instructions. Conventional liquid vaccines, such as DTP or hepatitis B, should absolutely not be frozen.
On the main shelves, medications should be positioned so that air can circulate freely between packages. Don't overcrowd the refrigerator. There must be a gap between the rows of packages for convection.
- ❄️ Rear wall: risk of freezing zone, placing vaccines closely is prohibited.
- 🌡️ Door shelves: unstable temperature zone, use is allowed only for dry materials or refrigerants in sealed containers.
- ✅ Central shelf area: the optimal place for storing most immunobiological drugs.
Particular attention should be paid to the height of the stacks. Tall pyramids of boxes block the access of cold air to the lower layers and can lead to local overheating. The optimal stacking height is no more than two rows of boxes.
Rules for using thermal containers and refrigerants
When transporting or temporary storage outside the main mode, thermal containers are often used. It is also necessary to maintain order inside them. Cold batteries must be pre-frozen at a temperature not lower than minus 18 degrees Celsius.
It is important to prevent direct contact of vaccines with ice blocks. Direct contact will lead to instant freezing of the drug at the wall of the vial, which will cause separation of the emulsion (for adsorbed vaccines) and loss of effectiveness. There should always be a layer of cardboard, fabric or a special separator between the refrigerant and the preparation.
The defrosting time of refrigerants also plays a role. If you are using them to maintain the temperature in the refrigerator during a power outage, they should be placed on the top shelf (cold air goes down) or around the perimeter, but not in close proximity to drug packages.
⚠️ Attention: Never place frozen cold accumulators directly on the bottom of the refrigerator under vaccine boxes without a protective layer. Condensation from melting ice can damage cardboard packaging and labels.
The amount of refrigerants is calculated based on the volume of the thermal container and the battery life. For a household refrigerator, during a planned power outage, it is recommended to freeze several bottles of water in advance and place them on the top shelf.
Temperature control and documentation
Without constant monitoring, all efforts for proper placement can go down the drain. Thermometers must be installed in the refrigerator compartment without fail. It is best to use minimum-maximum thermometers that show peak deviation values since the last reset.
Modern requirements often require the use of automatic thermal recorders (data loggers) that record temperature 24/7. This allows you to identify night surges or problems with the operation of the compressor that cannot be noticed during a visual inspection.
Temperature logging is a mandatory requirement for medical institutions and a recommended practice for home storage. Records must be made regularly, at least twice a day (morning and evening), indicating the date, time and instrument readings.
| Parameter | Standard value | Actions in case of deviation | Check frequency |
|---|---|---|---|
| Temperature (basic) | +2°C ... +8°C | Do not use the vaccine until clarified | 2 times a day |
| Temperature (freezing) | below -18°C | Replace refrigerants | once a week |
| Humidity (optimal) | up to 80% | Check seals | When cleaning |
☑️ Daily monitoring of the refrigerator
If the thermometer shows an out-of-range reading, vaccines must be immediately isolated and their suitability assessed. The use of temperature control indicators (VVM) on vials helps to quickly make a decision.
Typical errors and risks during storage
One of the most insidious mistakes is storing vaccines with food. Products can be a source of contamination and also occupy useful volume, disrupting air circulation. In addition, products often introduce heat when loaded.
Ignoring expiration dates and rotation rules is also common. The principle FIFO (First In, First Out - first to come, first to leave) must be strictly observed. Vaccines with expiring dates should be moved to an accessible zone, and new ones should be placed in depth.
Frequent and prolonged opening of the door is another enemy of stability. If you need to remove one bottle, do not hold the door open for several minutes while disassembling the contents. Determine in advance what exactly you need.
- 🚫 Shared storage: It is prohibited to store vaccines near food, chemicals or blood samples.
- 🧊 Freezing: Adsorbed vaccines (DTP, ADS-M, Hepatitis B) lose their properties when frozen, even once.
- 📦 Packaging: Storing vaccines without the original box deprives the drug of protection from light and mechanical damage.
⚠️ Attention: If you notice that sediment, flakes have appeared in the liquid vaccine or the color has changed, using such a drug is strictly prohibited, even if the temperature regime seemed to be observed.
What is a VVM indicator?
VVM (Vaccine Vial Monitor) is a heat-sensitive indicator on a vial that irreversibly changes color if the vaccine is exposed to elevated temperatures. If the inner square has become darker or merged with the outer circle, the vaccine is spoiled.
Compliance with these simple but critically important rules allows you to avoid financial losses and, more importantly, protects the health of patients from ineffective immunization.
Storage specifics for various groups of drugs
Different types of vaccines have their own characteristics. Live vaccines (eg, measles, rubella, mumps) are especially sensitive to heat and light. They should be stored in a place protected from light, preferably in the original packaging.
Adsorbed vaccines containing aluminum hydroxide as an adjuvant cannot be frozen. When frozen, the adsorbent precipitates and the vaccine becomes unusable. For such preparations, it is critical not to place them at the back wall of the refrigerator.
Dry vaccines (lyophilisates) are more stable, but after dilution with a solvent they must be used within 6-8 hours (or according to instructions) and stored in the refrigerator. You cannot prepare the solution in advance “in reserve.”
In conclusion, it is worth noting that proper storage is only part of the system. It is also important to monitor the technical condition of the refrigerator itself: the cleanliness of the condenser, the tightness of the rubber seals and the absence of ice.
Questions and answers (FAQ)
Is it possible to store vaccines in a regular home refrigerator?
Yes, it is possible if the refrigerator is able to maintain a stable temperature from +2 to +2 +8 degrees Celsius. However, it is not recommended to use No Frost system refrigerators without additional buffer capacity (containers with water), as they can greatly dry the air and create zones with different temperatures.
What to do if the refrigerator turns off for several hours?
Do not open the door again. If the outage lasted less than 4-6 hours and the door did not open, the temperature inside may not have had time to rise above +8°C. Check your temperature recorder or thermometer. If the temperature was normal, use vaccines. If in doubt, isolate and consult with the manufacturer.
How often do you need to defrost the refrigerator for storing vaccines?
The refrigerator must be free of ice. If you are using a drip system, defrosting is required as ice forms. To store medicines, it is better to use refrigerators with automatic defrosting or dry cold, but with mandatory humidity control.
Is it possible to place vaccines in a vegetable drawer?
It is strictly not recommended. The vegetable drawer (fruit drawer) is often the warmest part of the refrigerator or, conversely, an area with poor air circulation. The temperature there may not meet the required +2...+8°C.
Is it necessary to remove vaccines from the cardboard box?
No, it is not necessary. Cardboard packaging protects the drug from light, which can destroy the active components, and from mechanical damage. In addition, the box contains the series and expiration date, which is important for control.