Proper vaccine refrigeration is not a hit-or-miss proposition. Each year there are reports on how improper vaccine storage or other mishaps relating to vaccines result in loss of potency. This necessitates locating and revaccinating those who have received compromised inoculations plus the associated cost and inconvenience. Proper vaccine storage is also a critical element for complying with government-funded Vaccines for Children (VFC) programs.
Vaccine manufacturers are careful to note the proper storage temperatures for their products along what is called the cold chain of custody between manufacturing and inoculation. But manufacturers have little influence on the equipment used by healthcare facilities to maintain these temperatures. The CDC (Centers for Disease Control and Prevention) has stepped into this by issuing its 2016 Vaccine Storage and Handling Toolkit to provide comprehensive information on this vital activity. The Toolkit also covers in detail the importance of staff training and written standard operating procedures for handling vaccines in all situations.
What Not to Use for Vaccine Storage
Let’s get this out of the way first. There is no question that standard household refrigerators and freezers, commercial refrigeration units and especially dormitory-type refrigeration are recommended for vaccine storage. Instead, they should be placed in pharmacy-grade or biologic-grade laboratory refrigerators and laboratory freezers designed and equipped to maintain tight temperature tolerances. In this post you will learn important considerations when it comes to specifying vaccine refrigeration units for your practice along with information on associated monitoring, alarming and recording the performance of your units.
And as long as we’re at it, if your practice’s bean counters balk at the relatively higher cost of vaccine storage refrigeration counter the argument with the cost of lost product and inconvenience of re-vaccination. View your cold storage equipment as insurance against loss of vaccine potency by providing exacting temperature control. Vaccine refrigeration equipment is designed to do just that.
Vaccine Storage Temperature Requirements
As noted above vaccine manufacturers provide recommended storage temperatures for their products. In general, however, most refrigerated vaccines must be stored between 2⁰ and 8⁰C while frozen vaccines should be stored between -50⁰ and -15⁰C. Norlake vaccine refrigerators available from Tovatech feature digital LED display microprocessor temperature controls to set internal temperatures from +2⁰ to 10⁰C and are shipped factory set at 4⁰C. Norlake vaccine freezers, also featuring digital LED display microprocessor temperature controls, operate from -10 to -25⁰C and are factory set at -20⁰C. Lower temperature freezers are also available.
Vaccine Refrigeration Storage Capacity
This is an important consideration. Storage quantities of frozen vaccines are usually less than for refrigerated vaccines. In either case choose a unit with enough capacity to keep your supply in line with your needs and being aware of expiration dates.
How much should you store? In its 2016 Toolkit the CDC recommends that healthcare providers “should order and stock only enough vaccine to meet patient needs (typically for 60 days with a 30-day reordering cycle).” It notes that larger volumes increase the risk of wasting vaccines due to expiration or possible compromise due to failure of the refrigeration equipment.
The takeaway is that you should purchase refrigeration equipment sized to your requirements.
Here are some other considerations and suggestions regardless of the size of your equipment:
- Full refrigerators and freezers do a better job of maintaining internal temperatures. As you withdraw stock replace it with pre-chilled water bottles or frozen freezer packs.
- If your equipment has shelving on doors fill those shelves with water bottles or freezer packs – do not stock vaccines on door shelves. If you purchase new equipment select models without on-door shelving.
- Vaccine storage units are not food storage units – post a conspicuous sign to that effect.
- Keep contents in their original packages, store with early expiration dates toward the front, allow room for circulation between containers, and keep contents 2-3 inches from the walls and back of the unit.
Vaccine Refrigeration Temperature Alarming Systems
These are key points to CDC vaccine storage compliance. In the section above mention is made of failure of refrigeration equipment. Other causes of temperature excursions include doors left open too long or accidentally left ajar or the unit becoming unplugged, or a power outage.
We present here what is required regarding temperature alarming systems. Some of these are standard on vaccine refrigeration equipment while others can be added to bring vaccine scientific freezers and refrigerators into compliance.
Interior temperature monitoring is accomplished with product temperature sensors. Inserted in a bottle of glycerin or glycol these sensors mimic the temperature of refrigerated vaccines vs. internal air temperature.
Why is this? Since the variation in vaccine temperature is the important factor, the product sensors avoid unnecessary temperature alarms set off by routine door openings. Sensors may be used to record product temperature in two areas of the unit as well as internal air temperature.
Temperature controls range from simple dial-type thermostats with letters or numbers (cold, colder, coldest). A better method is a highly sophisticated digital microprocessor temperature controller that displays internal temperatures on an external LED.
Premium vaccine refrigeration systems use the more precise programmable logic controls, which is the best choice to maintain the absolute minimum temperature drift. High-end models also allow setting temperatures to one decimal place.
Temperature alarming is an absolutely critical feature when storing vaccines and is standard on many models of CDC-compliant vaccine refrigeration equipment. These are built-in digital audio and visual high/low temperature alarms, some with remote alarm contacts that can be connected to alert personnel elsewhere in the facility.
Otherwise compliant vaccine refrigeration equipment can be fitted with optional digital temperature alarms. These consist of internal sensors placed in bottles as described above. They are connected to an external control and display module.
Power outages are a separate concern. If your facility is not equipped with backup generators you should have in place detailed procedures to quickly move vaccine stock to an alternate location.
Monitoring and Record Keeping
Vaccine refrigerator and freezer temperature sensors collect data within the units for validation purposes. Procedures for monitoring and accessing data vary based on the system.
Built-in or free-standing temperature chart recorders can be used to collect temperature data 24/7 in hard copy form for storage and retrieval as needed. More recently these temperature chart recorders are being superseded by digital data loggers. When constructed to CDC requirements data loggers record the vaccine refrigeration unit’s internal temperature at the CDC required 15-minute minimum intervals, activate sound and visual alarms, and record the alarm duration. Data are downloaded from the digital recorder to a USB stick to be transferred to a PC for paperless record keeping.
An example of a data logger available from Tovatech is the Norlake ThermAlarm Data Logger with its detachable temperature probe in a glycol-filled bottle. It meets or exceeds current CDC-compliant vaccine storage and monitoring systems and comes with multi-point calibration on an individually-numbered Traceable Certificate which assures accuracy from an accredited ISO/IEC 17025:2005 (1750.01) calibration laboratory.
Whatever equipment is used to record temperatures keep in mind that the CDC recommends twice daily manual reviewing and recording temperatures displayed for the unit. The minimum and maximum temperatures since the previous reading should also be noted to determine if temperatures are out of range.
Auto Defrost vs. Manual Defrost Vaccine Refrigeration
This is an important topic. There are three systems – automatic defrost, frost-free and manual defrost.
Choose an auto-defrost unit for refrigerated vaccines. Most models have fans that circulate chilled air throughout the unit. This has the advantage of creating a uniform internal temperature.
Auto defrost refrigerators have a timed defrost cycle that turns off the compressor but keeps fans running to remove frost accumulation on the coils. Certain models of auto-defrost lab refrigerators allow users to control the frequency and duration of the defrost cycle. As noted earlier in this post, filling the unit with vaccines or water bottles helps reduce temperature fluctuations due to compressor cycling and door openings.
The CDC has recently recommended the use of auto-defrost or frost-free freezers for vaccines. These units also have a timed cycle during which heaters melt the ice accumulated on the coils. Both auto-defrost and frost-free models use a forced air refrigeration system to circulate refrigerated air throughout the cabinet to prevent condensation and ice buildup on the interior surfaces.
Note that while manual defrost freezers provide greater temperature stability and allow full control over the defrost cycle they must be shut down on a regular basis for defrosting. Therefore backup freezers are required to protect the vaccines.
Other Selection and Usage Criteria for Vaccine Storage Units
Here are some other important checkpoints to keep in mind when selecting vaccine refrigeration equipment:
- Stand-alone lab and pharmaceutical-grade refrigerators and stand-alone freezers are definitely preferable to combination refrigerator-freezers. The reason is that they provide more exacting temperature control. Stand-alone CDC-compliant units are available in a broad range of capacities from small countertop models to large 3-door units.
- If you must use a household-grade combination refrigerator/freezer unit, only use the refrigerator compartment for storing vaccines. These units have cold spots and temperature fluctuations. Air circulating from the freezer could expose refrigerated vaccines to freezing temperatures. Therefore keep the vaccines away from the cold air vent.
- Refrigerators with visible cooling plates or coils on the back wall are not acceptable. Contact with these plates can cause refrigerated vaccines to freeze.
- If you are purchasing a new unit remember that the CDC says on-door storage of vaccines is unacceptable due to enhanced exposure to ambient temperatures.
- If your existing equipment is otherwise compatible with CDC guidelines (or can be made compatible, see temperature control and monitoring sections above) fill on-door shelves and bins with water bottles or freezer packs.
More Suggestions for Safe Vaccine Storage
This section could also be called “why didn’t I think of that?”
- Be certain that enough physical space is available and that there is proximity to a power outlet – dedicated is preferable; extension cords are not recommended.
- Built-in (undercounter) vs. free-standing units. Built-in units do not require space at the sides and back because they are vented from the front. Free-standing units generally require space at the sides and top for air circulation.
- Side, top and rear clearances for full size units. Manufacturers’ specifications indicate these requirements. Most models are designed for freestanding use and require 2-4 inches on all sides to allow air circulation.
- Will the undercounter vaccine refrigerator or freezer fit in existing or planned casework? If so is there enough clearance to allow the equipment to function properly?
- Local environment. Avoid placing the equipment near heating ducts or in areas of direct sunlight. Allow enough space for the unit to be moved for servicing.
We hope the information in this post is useful when specifying vaccine refrigerators and freezers for your healthcare facility. For additional information and recommendations on selecting equipment please call the vaccine storage professionals at Tovatech for expert advice on the right model for your clinic.