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Immunizing agents are biologic materials that are subject to gradual loss of potency from deterioration and denaturation. Loss of potency can be accelerated under certain conditions of transport, storage and handling, and may result in failure to stimulate an adequate immunologic response, leading to lower levels of protection against disease. Conditions that result in loss of potency vary among products.
The province or territory should follow Public Health Agency of Canada guidelines to ensure that the manufacturer monitors the cold chain during the shipment of vaccine. Also, the province or territory should have a standard for monitoring shipments to regions, public health units and private offices. Manufacturer and NACI recommendations generally specify that most products should be stored at temperatures from +2º to +8º C. Exceptions exist (e.g., yellow fever) for which the recommended storage conditions are -30º to +5º C, as outlined in the manufacturer's product leaflets.
The term "cold chain" as used in this statement refers to all equipment and procedures used to ensure that vaccines are protected from inappropriate temperatures and light, from the time of transport from the manufacturer to the time of administration.
The effects of exposure to adverse environmental conditions, such as freezing, heat and light, are cumulative. Data are available to indicate that certain products remain stable at temperatures outside of +2º to +8º C for specified periods of time, but mechanisms rarely exist for monitoring the effect of cumulative exposures. Additionally, different products are often transported and stored in the same container. Therefore, it is recommended that all biologics for immunization be maintained at +2º to +8º C at all times, unless otherwise specified in the product leaflet. Management of products that have been exposed to adverse conditions should be guided by specific instructions pertaining to the conditions from the vaccine supplier.
Monitoring of the vaccine cold chain is required to ensure that biologics are being stored and transported at recommended temperatures. Testing of product potency or seroconversion rates as indicators of cold chain integrity are rarely feasible.
Refer to the product leaflet of each immunizing agent for specific instructions related to storage and handling. The following general principles apply.
Multidose vials should be removed from the refrigerator only to draw up the dose required and should be replaced immediately. Although the practice of drawing vaccines and leaving them in the refrigerator in advance of administration is strongly discouraged (see the Vaccine Administration Practices chapter), two exceptions are noted:
Vaccine providers should observe strict aseptic technique when using multidose vials. Multidose vials should be dated once entered and used only for the period of time specified in the manufacturer's product leaflet. If no directions are given the vaccine should not be used beyond 30 days after initial entry into the vial.
For optimal potency, freeze-dried vaccines (e.g., measles, mumps rubella [MMR], varicella, Bacille Calmette-Guérin [BCG], Haemophilus influenzae type b) should be reconstituted immediately before use with the diluent provided for that purpose. Reconstituted vaccines, including yellow fever vaccine, should be used within 1 hour of reconstitution; if unused, they should be discarded. There are slight variations in the time intervals recommended by specific manufacturers, and users should refer to the product leaflet to guide timing of reconstitution.
MMR, varicella and BCG vaccines should be protected from light at all times by storage of the vials in the cartons provided. After reconstitution, if vaccines are not used immediately, they must be kept at +2º to +8º C, protected from light and used within the time frame recommended in the product leaflet.
Vaccine providers are reminded that the maintenance of cold chain also requires that vaccines not be exposed to temperatures lower than those recommended. Liquid inactivated and adsorbed vaccines should not be used if they have been frozen. These include Tdap, DTaP, DT, DTaP-Polio, DT-Polio, Td, Td-Polio, hepatitis A and B vaccines, influenza, pneumococcal and meningococcal vaccines. Before use, liquid vaccines should be inspected and should not be used if the usual appearance is altered or a temperature recording device shows that the vaccine was exposed to temperatures below zero.
Vaccines should not be used beyond their expiry date. For expiry dates specified as month/year, products are deemed to expire on the last day of the specified month. The error of administration of expired vaccine should be reported to the local public health authority.
All vaccines that cannot be used because of expiry or adverse environmental exposure should be returned to the source for appropriate recording of returns and disposal or should be appropriately disposed of according to local or regional standards.
The temperature in frost-free refrigerators may cycle widely and should be monitored to ensure that cycling is within the acceptable range. Special maximum-minimum thermometers are commercially available for purchase and are useful for most office storage. Vaccine providers should record daily current maximum and minimum refrigerator temperatures and contact the local public health unit if vaccines are exposed to temperatures outside the recommended range. More expensive, constant chart-recording thermometers with alarms are appropriate for larger vaccine storage depots. Non- frost-free refrigerators should be defrosted regularly and immunizing agents stored in a functioning refrigerator during the defrosting process. Refrigerators older than 10 years are more likely to malfunction and to have breaks in the seal around the door, leading to temperature instability. Half-size/under the counter/bar refrigerators are less reliable than full-size kitchen refrigerators. Vaccine providers in private practice will discover that the cost of replacing ageing bar refrigerators with newer and full-size equipment is offset by the savings in hydroelectric power and staff time dealing with reporting and fixing cold chain breaks.
Placement of full, plastic water bottles in the lower compartment and door shelves of the refrigerator and ice packs in the freezer compartment will help stabilize temperatures, especially in the event of a power failure.
The following office procedures should be implemented to ensure that storage of vaccines is optimized:
Ongoing cold chain monitoring should be integrated into immunization practice. Periodic cold chain surveys are worthwhile to evaluate awareness, equipment and practices as well as the frequency of breaks in the cold chain during transport from depots and storage in peripheral offices. These should be undertaken by provincial/territorial and local immunization programs.
Further information is available online in the National Vaccine Storage and Handling Guidelines for Immunization Providers (2007). This resource was developed by the Cold Chain Management Task Group of the Canadian Nursing Coalition for Immunization (CNCI).
Note: While this document is not a NACI document, it supports the achievement of the General Guidelines in Part 1 of the Canadian Immunization Guide - which is developed and approved by NACI.
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