For more than 200 years, since Edward Jenner first demonstrated that vaccination offered protection against smallpox, the use of vaccines has continued to reduce the burden of many bacterial and viral diseases. Vaccination not only protects individuals, but also others in the community, by increasing the general level of immunity and minimising the spread of infection.
The ‘cold-chain’ is the system of transporting and storing vaccines within the temperature range of 2°C to 8°C from the place of manufacture to the point of administration. This temperature range is recommended because outside this range vaccines may (very quickly) lose their potency. Immunisation service providers should maintain their vaccine refrigerators as close as possible to 5°C, as this gives a safety margin of + or − 3°C. World Health Organization’s Expanded Program on Immunization (EPI) has developed detailed guidelines on the maintenance of an effective cold-chain. Maintenance of the cold-chain system requires that processes are in place to ensure that a potent vaccine reaches recipients. Apart from invention of new heat stable vaccines, the improvisation in cold chain and the understanding of the ideal methods of vaccine storage and transport by officials, doctors and field staff are the factors for the reduction of mortality and morbidity due to vaccine preventable diseases. However, evaluations in many developing countries had showed that there were still weak points in cold chain performance and that more attention should be paid to it, especially in peripheral set ups. The vaccines which are not stored in the recommended temperature range gets degraded. Not only vaccine exposure to the higher temperature but freezing also causes degradation and consequently total or partial loss of potency. Commonly the degradation rate of a vaccine is determined by the storage temperature: the higher the temperature, the more rapid and extensive is the degradation. There are considerable differences between degradation rates for different vaccines.In spite of knowing all these facts, still at many places vaccines are not being stored and transported properly. This leads stocks of vaccines exposed for varying periods to elevated temperatures/ freezing. Questions are often raised as to whether such vaccine is enough potent to give protection needed to it’s recipient? what should be done with the stock of such vaccines?
Practically majority of the practicing doctors use domestic refrigerator to store the vaccines with a belief that the vaccines will be safe. Domestic refrigerators and industrial refrigerators used for the vaccine storage are designed only for the storage of food and drink and usually have several temperature zones to meet the requirements of different foods. They are not designed for the special temperature needs of vaccines and place the safety of vaccines at risk. For vaccine storage the domestic refrigerator suffer from following drawbacks:
::Temperature varies significantly every time the door is opened
::Temperature rises during defrosting in cycle in cyclic defrost and frost free refrigerator
::Cabinet temperature is easily affected by ambient temperature
::Temperature setting using dial is crude and inaccurate.
Hence the domestic refrigerators requires modifications before it is used to store the vaccines. ‘Frost-free’ rather than cyclic type domestic refrigerators are recommended for storage of vaccines.Cyclic Defrost refrigerators are not recommended to use to store vaccines as they produce wide fluctuations in the internal temperature with regular internal heating. Bar refrigerators in particular are strongly not recommended because of risk of temperature instability, freezing, risk and susceptibility to ambient temperature. Frost free refrigerator do not have heating cycles but have low level warming cycles. They usually have several temperature zones. In this refrigerator it is not necessary that the top self is the coldest part of the unit.
Do not use ‘multi-flow’ refrigerators that direct air from the freezer compartment to the main cabinet. These types of refrigerators can easily be recognised by the presence of 2 thermostat controls.
Domestic refrigerators that have a separate freezer compartment are recommended for vaccine storage. Safe vaccine storage is possible in most refrigerators if the following procedures or modifications are carried out and standards are maintained:
::store vaccine in a dedicated refrigerator if possible. Do not store food or drink in vaccine refrigerators.
::The refrigerator maintains temperatures without fluctuating into the danger zones (<+2°C, >+8°C). The refrigerator compartment should maintain temperatures between 2° - 8° Celsius . The freezer compartment should maintain temperatures at or below 5° F (-15° C).
::The refrigerator has not required repairing for last 2 years
::The refrigerator is free of any water or coolant leaks.
::The seals are in good condition and are sealing tightly.
::store vaccines only on the middle and upper shelves in the refrigerator;
::The door closes properly automatically on leaving it free.
::The refrigerator compressor is quiet – does not make sound.
::The refrigerator is of an adequate size for the individual storage needs.
::The domestic refrigerator with separate freezer compartment are recommended, as it is easier to maintain the correct temperature.
::The staff have relevant knowledge of vaccine storage, which is detailed in written protocol.
Tips for better vaccine storage in domestic refrigerators:
A. Placement of refrigerator
::Refrigerator should be placed out of direct sunlight & away from heat ::Accessibility: Ensure the vaccine refrigerator is in a secure area accessible to staff only to minimize the risk of unnecessary door opening, power being switched off at the power point
B. Recognize individual vaccine refrigerator
Before starting storing the vaccines identify
::which are the cold and warm areas in your refrigerator ?
::What are the temperature variations from top to bottom and from back to front?
::What happens to refrigerator temperature in cold and hot weather?
::What happens if there is lot of use or no use in holidays or in weekends?
::Be aware of how to manage a refrigerator effectively i.e. where the air vents are and how to adjust the thermostat, vents, air outlets, shelves positioning, freezer, doors, etc.
Identify the ‘cold spots’ of the refrigerator with help of recording device (data logger / thermometer probe) needs to be left in each position for a minimum of 2:: hours. Each shelf of the refrigerator is the key area for monitoring.
C. Stabilize the temperature of the refrigerator before stocking
The refrigerator temperature needs to be stabilized before using for vaccine storage.
Monitor the refrigerator temperatures closely until they have stabilized.
D. Monitoring temperatures inside the refrigerators.
Ensure that each domestic refrigerator storing vaccine has a Celsius digital minimum - maximum thermometer. A thermometer should be placed in a central location within the storage compartment,
:: Check the accuracy of thermometer once in 12 months.
::Change the thermometer battery every 12 months or as and when needed.
:: A temperature recording chart is required to document minimum and maximum temperatures. This written record enables staff to monitor and take action if temperatures go outside the recommended range.
E. The power source
Avoid Accidental disconnection from the power source :Accidental disconnection from the power source if unnoticed for a long period can cause heat damage to vaccines,. Ensure the power source is marked clearly in a way to prevent the refrigerator from being accidentally unplugged or turned off .
Ensure proper Power backup: Do not switch off power supply of refrigerator when there is failure in the main power supply. Arrange for alternative power-supply which very well backs up load of at least one refrigerator also.
F. In the freezer, place water bottles or ice packs/gel packs
This will assist in stabilizing the temperature in refrigerator compartment as in most frost-free refrigerators cold air is distributed from the freezer to the fresh food compartment.
This will also help to stabilize freezer temperatures and ‘on-off’ cycling of the refrigerator
It will be available for vaccine transport also.
G. Fill lower drawers and door with water filled plastic containers.
Using cooled water bottles will help stabilize the temperature by increasing the ‘cold mass’ i.e., it keeps the temperature inside the refrigerator more stable
It reduces warming periods when the refrigerator is opened. This is particularly useful if there is a power cut or other cause of refrigerator failure.
H. Store the vaccines in enclosed plastic containers :
This will allows easy identification of vaccines and minimizes the time spent with the door opened searching for vaccines.
::Label containers / drawers clearly with name(s) of vaccine(s).
::The box and leaflet (product information) provide some further protection from very short term fluctuations e.g. after the door is opened and closed.
::Enclosed plastic containers will help to stabilize temperatures a little and provide some protection in borderline freezing episodes as well as against effects from the cooling plate and blasts of cold air from outlets.
::Air circulation between enclosed plastic containers is necessary to maintain a more constant ambient temperature.
::Do not crowd the vaccines by overfilling the shelves. Allow space between containers for air circulation.
::Storage of vaccine against refrigerator walls increases the risk of freezing. It is necessary to ensure a space between enclosed plastic containers and the cooling plate. Ensure a gap of at least :: cm from all refrigerator Keep a distance of at least 2 cms above and below the vaccine container to allow free air circulation.
::Vaccines must never be stored in the door of the refrigerator.
::Place freeze-tolerant vaccines (Measles, Mumps, Rubella, OPV and BCG) in the shelves identified as being the coldest and freeze-sensitive vaccines (DTP containing vaccines; Hib, Pneumococcal, Influenza, Hepatitis, IPV and some varicella vaccines) on shelves identified as having more stable temperatures (e.g. no ‘cold spots’).
::Rotate stock so vaccines with the shortest expiry date are used first.
I. Keep the door closed as much as possible
Reducing door opening helps to keep internal temperatures stable.
::Vaccine refrigerators should have a sticker to remind staff
::Stick a basic map of vaccine locations on the outside of the refrigerator door so, staff can go ‘straight’ to the vaccine when the door is opened.
::Do not open the door fully while using, keep it to minimum sufficient for the need.
::Installing a ‘door is open alarm’ can be helpful
::A refrigerator with glass door & curtain on it can help reduce opening time while reaching particular vaccine as it can be visualized from the door
J. Alarm Systems
Install a security/alarm system which will give a warning if:
::The temperatures rise or fall outside normal ranges
::There is power failure
::The door is left open
Such alarms can have different options like it can alert a guard, notify designated staff, and summon someone situated remotely by telephone ring, audio intimation, etc.
K. Training & assigning staff
Good vaccine storage & handling depends on knowledge & habits of the staff
::Training ensures that everyone handling vaccines knows how to protect them
::Ensure that one person is responsible for adjusting refrigerator controls & who is responsible for cold chain management to enable consistency.
L. To develop own documented protocols and procedures for vaccine storage
M. Immediate identification of breach in cold chain and it’s management
In order to ensure that effective vaccine is administered it is important to promptly identify and manage cold chain breaches. Establish and document protocols for response to cold chain breaches. This will minimize the risk of ineffective vaccine being administered. All staff should be aware of these protocols.
N. Vaccine storage self-audit
It is important to self-audit vaccine refrigerator as part of a routine quality assurance and risk management process. It also enables you to have confidence that you are administering safe and effective vaccines.
O. Ordering vaccine:
::Keep vaccine stock to a minimum by regularly ordering only the quantity of vaccine required for the period until the next delivery.
::Order vaccine sensibly; do not over order to get incentives.
::Conduct monthly inventory counts.
P. Maintenance of the vaccine refrigerator
::Report breakdowns immediately and arrange for alternative monitored storage for vaccines while the refrigerator is repaired.
::Regularly check the refrigerator seals to ensure that a good seal is maintained.
::Replace the seals if they are damaged or cold air is leaking from the refrigerator.
::If there are exposed coils on the back of the refrigerator keep them clean and dust free to improve operating efficiency.
Q. Defrosting or cleaning
::Defrost refrigerator regularly,
::Regular defrosting also aids in the efficient functioning of refrigerator.
::During defrosting or cleaning of the refrigerator, move the vaccines to a second refrigerator. This temporary storage refrigerator must also be monitored to ensure the correct temperature is maintained. Alternatively the vaccines can be stored in a precooled insulated container with ice packs or ice until the normal vaccine refrigerator is ready for use again.
Purpose-built vaccine refrigerators
Purpose-built vaccine refrigerators are the preferred refrigerators for vaccine storage. It is recommended that if possible purpose-built refrigerators are used by larger vaccination services, including hospitals, pharmacies, larger community health centres and larger general practices. It is also recommended that they be used in remote settings. they are considerably more expensive than domestic refrigerators. The Purpose built refrigerators have following advantages over the domestic refrigerator :
::Do not required to be modified for vaccine storage .
::They are programmed to maintain an internal temperature between 2°C to 8°C, ::cabinet temperature is not affected by ambient temperature and is stable and uniform.
::Defrost cycle allowing defrosting without rise in cabinet temperature
::They automatically defrost
::They have an external temperature reading display and a maximum/minimum temperature continuous display, and an alarm for deviations outside the programmed temperature range.
::Less demanding maintenance then domestic refrigerator.
::Good temperature recovery- when the fridge is open to access the vaccines
::Nearly all internal space can be used to store the vaccines, so the size of the purpose built refrigerator may be smaller then the previously used domestic refrigerator.
Before purchasing the purpose built refrigerator try to answer following questions:
::How big does my refrigerator be?
::What will be maximum amount of vaccines I will need to store?
::Do I have space in my clinic?
::If I do not by the purpose built refrigerator, what will be risk to my clients? What is my legal risk?
How to choose good purpose built refrigerator?
Before purchasing the purpose built refrigerator consider following points:
::What type of Alarm facility it is having? Does it have door open alarm ?
::The temperature recording system may be visual or chart system. Ensure that the temperature recording system can be easily read and accessible.
::Does the temperature probe have appropriate lagging device?
::Does it have easy to use minimum/maximum temperature display system?
::Does it need enhancements? ( alarms, temperature monitoring features etc, What shall be cost?)
::Can the refrigerator record how long it has remained in power failure state ?
::In power failure state how long it will stay in recommended temperature range?
::What size of space will it have?
Even if you use Purpose built refrigerator for storing the vaccine , temperature needs to be monitored and recorded regularly daily. The glass door of the PBR may not have UV light filter and in this case the vaccines should be protected from UV light by keeping them in their original packing.
Maintaining and monitoring refrigerator temperatures
To measure the temperature during storage of vaccines, different type of thermometers are used. Minimum/maximum thermometer is essential requirement for temperature monitoring during vaccine storage and transport. The minimum/maximum thermometer should be placed on a middle shelf and temperatures should be checked and recorded daily. The most effective minimum/maximum thermometer is a digital type with a probe. If using a digital thermometer with a probe, place the probe directly in contact with a vaccine vial or package. The refrigerator temperature should be read around the same time each day, preferably prior to each working day. Minimum/maximum thermometer must be reset regularly, the thermometer batary must be checked and replaced time to time and one should choose a thermometer which records temperature in celcius.
Dial Thermometers
Dial thermometers have been provided to record the temperature in the ILRs/Freezers. One dial thermometer should be kept in every unit.
Alcohol Stem Thermometers
Alcoholic thermometers are much sensitive and accurate than dial thermometers. They can record temperatures from – 500C to + 500C and can be used for ILRs and deep freezers.
Additional equipments for vaccine storage:
Automatic Voltage Stabilizer
The function of the voltage stabilizer is to control the range of fluctuations in the main voltage of 220 Volts (+ 10 volts) .No electrical Cold Chain equipment should be used/operated without a Voltage Stabilizer. Before installation and use, familiarize yourself with the various features of the Automatic Voltage Stabilizer
Cold Boxes

Cold boxes are big insulated boxes. These are of two sizes: 5 litres and 20 litres with requisite number of ice packs. Cold Boxes are mainly used for transportation of vaccines from district store to the PHC. In emergency they can also be used to store vaccines as well as frozen ice packs as icepack bank. Before the vaccines are placed in the cold boxes, fully frozen ice packs should be placed at the bottom and sides of the cold box. The vaccines should be placed in cartons or polythene bags and then placed in the cold box. The Vaccines are to be covered with a layer of fully frozen ice packs and the cold box is then closed. The vials of DPT, DT, Hep.B and TT vaccines should not be placed in direct contact with frozen ice packs and should be surrounded by OPV vials.
Note that vaccines should be transported/stored in cold boxes only with sufficient number of hard frozen ice packs.
Note: Hard frozen ice packs (frozen at –200C) should be conditioned before laying out in the cold box. This will protect `T’ series vaccine from getting frozen.
How to keep Cold Boxes in good condition when not in use
:: Clean with detergent and dry after every use
:: Examine inside and outside surface after every use for cracks
:: Check that the rubber seal around the lid is not broken; if broken, replace immediately
:: Adjust the tension on the latches so that the lid closes tightly
::Lubricate hinges and locks routinely
Vaccine Carriers
Vaccine carriers are used by health workers for carrying vaccines (16-20 vials) to sub-centres or to villages. They maintain the cold chain during transport from the PHC for one day’s use in the field. Vaccine carriers have thick walls and lids and are made of a special material that prevents heat from passing through and reducing the potency of vaccines. The inside temperature of a vaccine carrier is maintained between +2 to +8 degrees centigrade with :: frozen ice packs for one day (if not opened frequently).
::Only vaccine carriers with :: ice packs should be used. Day carriers with 2 ice packs should not be used.
::Do not leave vaccine carriers in the sunlight; this spoils vaccines that are sensitive to heat and light.
::Do not open the lid unnecessarily as this can allow heat and light into the carrier, which can spoil vaccines.
::Do not drop or sit on the vaccine carrier: this can damage the carrier.
::Do not carry vaccines in handbag as this can spoil vaccines that are sensitive to heat.

WHO recommended vaccine storage conditions :

Checklist for Preventive Maintenance



::Safeguarding Vaccines During Immunisation Sessions
::Keep refrigerator door/cooler openings to a minimum.
::Reconstitute vaccines immediately prior to administering.
::When the vaccines are outside the vaccine carrier, keep them out of direct sunlight and away from other sources of heat and ultraviolet light (e.g. fluorescent light).
::Avoid handling vaccines any more than absolutely necessary. Take vaccine (and diluents if needed) from the cooler only as required.
Reconstitution of vaccine:
::Diluents are specifically designed for the needs of each vaccine, and therefore, are not interchangeable.
::Do not use diluents warmer than the vaccine as they can affect the potency of live vaccines, Diluents need to be the same temperature as the vaccine at the time of reconstitution.
::Use the entire volume of the cooled diluent supplied when reconstituting the vaccine.
::Reconstituted vaccines should be used within one hour (30 minutes for Varicella), providing they have been kept between +2°C to +8°C and protected from sunlight and fluorescent light.
::Reconstituted MMR can be stored in the plastic syringe in a dark place between +2°C to +8°C without loss of potency for up to eight hours .
::Planning outreach immunization
::Plan the session carefully.
::Ensure you take a sufficient stock of vaccine, diluent, adrenaline and ice packs.
::Place new, unfrozen ice packs/gel packs in the freezer so they will be ready for the next working day.
::If doing immunization sessions outdoors, choose a cool shaded site.
::For a mobile service where there is no electric power supply or refrigerator, take an extra cold box containing extra ice packs/gel packs.
Power Failure

::During a power failure of :: hours or less the refrigerator door should be kept closed.
::If the back-up generator facility is lacking, identify an available unit at another nearby site.
::Before moving vaccine, call the alternative storage site to ensure that the back-up generator is working.
::In situations where a location with a back-up generator can not be identified within a reasonable distance, preparations should be made to have coolers and gel packs ready to temporarily and safely store vaccine.
::If a refrigerator with a backup generator has not been located or is not working, & for power failures more than :: hours store vaccines in a cooler with conditioned ice packs/gel packs.

::Continue to monitor the temperature of the vaccines by placing the thermometer probe inside a vaccine box inside the cooler.
Refrigerator Failure
::If it is found that the refrigerator is not working properly, do not open it unless the vaccine must be retrieved.
::Call maintenance personnel immediately.
::If the refrigerator cannot be repaired quickly and with vaccine safety, move the vaccines.
Cold Chain Breach
::Immediately isolate the vaccines until you have been in touch with the relevant authority
::Keep vaccines refrigerated between + 2°C and +8°C and label ‘do not use’.
::Do not discard any vaccine until advice has been sought
::For privately purchased vaccines contact the manufacturer for advice.
Stability of vaccines at different temperatures:
High temperatures affect all vaccines whereas freezing damages only some vaccines.
The following vaccines are unstable at room temperature:
::BCG (Bacille Calmette-Guérin) vaccine
::Measles-mumps-rubella (MMR) vaccine


::Oral poliomyelitis vaccine (OPV)
::Varicella-zoster vaccine
::Yellow fever vaccine
::All reconstituted vaccines
Do not freeze the following vaccines:
::Diphtheria-tetanus-pertussis containing vaccines
::Haemophilus influenzae type b (the exception being the lyophilised PRP-T vaccines)
::Hepatitis B-containing vaccines
::Hepatitis A-containing vaccines
::Influenza vaccine
::Pneumococcal (polysaccharide and conjugate) vaccines
::Meningococcal C conjugate vaccines
::Japanese encephalitis vaccine
::All reconstituted vaccines
::All combinations of these vaccines
::Rabies vaccine
::Vaccine diluents
Note: If vaccines listed above have been exposed to temperatures 0°C and below, do not use.
The following vaccines must not be exposed to light:
::BCG (Bacille Calmette-Guérin) vaccine
::Reconstituted measles-mumps-rubella (MMR) vaccine
::Monovalent rubella vaccine
::Oral poliomyelitis vaccine (OPV)
::Varicella-zoster vaccine (VZV)
::Most DTPa-containing vaccines
::Meningococcal C conjugate vaccine
::Yellow fever vaccine.