On December 31, 1999, the National Millennium Time Capsule was placed in the ground in Washington, DC. This capsule contains a number of items that are felt to represent the greatest achievements of the past 1,000 years. Six vials of vaccine were selected to represent the greatest accomplishment in the field of medicine during that time. An even more poignant and lasting symbol is the improved health and vitality of current generations of children who have avoided the "rite of passage" known as childhood diseases.
Vaccines are modern miracles. As a result of their use, literally millions of children who would have died of diseases are alive today. Vaccines have been administered in storefronts, under banyan trees, on the frozen tundra, and at desert oases. The common thread that allowed all of these vaccines to provide the protection afforded by their components was a simple one. The individuals handling these vaccines knew that, to provide protection from disease, it was necessary to protect them from exposure to adverse conditions.
Relatively few health care practitioners in the United States need to administer vaccine under the conditions present in less developed areas of the world. Because of the availability of electricity, refrigerator-freezers, and good transportation systems, few of us believe that handling vaccines is a problem. However, if we examine the total number of doses of various vaccines being administered in the United States (Centers for Disease Control and Prevention, unpublished data, 1996-1 999), ] we find that we are using significantly more vaccine than the current birth cohorts warrant. A portion of the vaccine purchased, but not administered, is lost to us because of mishandling. Mishandling may also result in children's receiving vaccines of reduced effectiveness.
A practice that provides a full series of vaccines to as few as 50 children may pay more than $30,000 annually for vaccines. This calculation is based on pricing from commercial catalogs and the Advisory Committee on Immunization Practices' Recommended Childhood Immunization Schedule, January-December 2001. If a practice has children who are enrolled in the Vaccines for Children program, the cost for vaccine for 50 children is less (approximately $18,000 annually) because this program purchases vaccine from a contract negotiated by the Centers for Disease Control and Prevention at a discounted rate. However, the cost of vaccines is a substantial expense to pediatricians or to the nation's taxpayers. The cost may be reduced if some care is taken to avoid mishandling vaccines. Mishandling can include leaving a box of vaccine on the counter, storing in the freezer vaccine that should be stored in the refrigerator, and ordering more vaccine than can be used before the expiration date.
Pediatricians should keep the following suggestions in mind when storing and handling vaccines.
Vaccine should be stored in a full-size refrigerator with a separate freezer compartment. The use of dormitory-size or apartment-size refrigerator-freezer combinations is not recommended because these small refrigerators are generally not sufficiently well insulated to ensure temperature stability. Ideally, health care facilities should purchase a commercial-quality refrigerator with a separate freezer compartment.
Vaccine should be stored in its own refrigerator, not in one that also contains food and drink. People have a tendency to "gaze and graze" when looking at a variety of food or drink. Such behavior could subject vaccines to extreme variations in temperature.
In some instances, there is room for only one refrigerator at a location. If this is the case, all staff members need to be diligent about the storage of items other than medical supplies in the refrigerator.
Vaccine should never be stored on the door of a refrigerator. The door has less insulation and the vaccine would be subjected to greater extremes in temperature when the door was opened.
The temperature should be read and recorded at least twice each working day. Refrigerator compartments should be maintained at a temperature of 2°C to 80C (35°F to 46°F). Freezer compartments used to store varicella vaccine should be maintained at -15°C (5°F).
Varicella vaccine that is stored at warmer than recommended temperatures may not remain viable until the expiration date printed on the vial. Health care providers should contact the manufacturer to determine whether the vaccine is still usable if it has been exposed to temperatures beyond the recommended storage range.
It will be necessary to have a thermometer in each compartment to ensure that the appropriate temperature range is being maintained. Large practices that store significant quantities of vaccine may want to have a temperature monitoring system installed so that the staff can be alerted if there is a power failure or some other interruption of the cold chain and vaccine can be moved to a secure location. Brayden and France have suggested leaving a tray of ice cubes upside down in the freezer to provide a visual reference to ensure the maintenance of a constant temperature if a temperature monitoring system is not available.2
Movement of vaccines in the event of a power failure requires an insulated container, frozen ice packs, and a new location with room to store the vaccines. In some cases, power outages of less than 24 hours will not affect the vaccine if the door of the refrigerator is left shut and the contents of the freezer do not thaw. However, if the office is hot, the temperature in the refrigerator and the freezer compartments should be monitored more carefully.
Staff should be taught the correct temperature range to be maintained in the refrigerator and the freezer compartments and how to read and record the temperatures. They also need to know whom to contact if the temperature is not in the appropriate range.
The most common problem that affects vaccines is inappropriate storage temperatures. Most individuals suspect that vaccines stored at warm temperatures are at greatest risk. Actually, with the exception of varicella vaccine, the greatest risk to vaccine is storage at a temperature below freezing.
All routine childhood vaccines (with the exception of varicella vaccine) should be stored at 2°C to 80C (35°F to 46°F). Diphtheria and tetanus toxoids and acellular pertussis, pneumococcal, inactivated poliovirus, Haemophilus influenzae type b, hepatitis A, hepatitis B, and influenza vaccines should never be frozen. Measles-mumpsrubella (MMR) and varicella vaccines may be stored in a freezer. In most cases, MMR vaccine is stored in the refrigerator compartment. Although there are some exceptions to the general rule regarding freezing, it is probably easiest to instruct the staff to place only varicella vaccine in the freezer.
Staff should be trained to react to refrigerator temperatures that approach 2°C (35°F). Temperatures should be maintained in the middle of the range, not at the extremes.
A temperature monitoring system should be installed on the refrigerator and freezer areas where vaccine is stored. An alternative is a minimum-maximum thermometer to record the temperature extremes when no one is in the office.
The ability to ensure that vaccine has been maintained at the appropriate temperature is important. Varicella vaccine needs to be maintained at -15°C (50F). To do this, many practices turn the temperature control down in their refrigerator-freezer combinations. This often results in the temperature's being lowered in the refrigerator section and the freezer compartment. If the freezer temperature is adjusted, it will be necessary to monitor the refrigerator section for several days to ensure that the appropriate temperature range is being maintained. The easiest way to accomplish this monitoring 24 hours a day, 7 days a week, is through the use of a temperaturerecording device.
VACCINE SUPPLIES AND INVENTORY
Pediatricians should maintain no more than a 1- to 2-month supply of vaccine. Selecting the optimal amount of vaccine to be kept on hand is always a balancing act. No one wishes to run out of vaccine. To avoid this situation, some pediatricians attempt to stockpile vaccine. This may result in wasted vaccine. Often the desire to "have enough" results in the practice having too much and the vaccine expiring because it cannot be used in time.
Another risk of stockpiling is the possibility that the temperature range will be exceeded because of power outages, refrigerator doors being left slightly open, the building maintenance staff turning off the electricity to work on something, or the housekeeping staff unplugging the refrigerator to run the vacuum cleaner and forgetting to plug it back into the socket. The vaccine can be rendered ineffective because of a failed cold chain, but there may be no obvious way to detect the failure. Housekeeping and maintenance staff can be alerted by posting "Do not unplug or turn off this appliance" signs on the electrical outlets or breaker panels that control the refrigerators and freezers.
An inventory of vaccine should be conducted every month. This allows the staff to order vaccines that will be used during the next several weeks. The inventory also ensures that the vaccines with the earliest expiration dates are used first. The principle of "first in, first out" usually ensures that most vaccines will be used before they expire. If the practice has several locations, vaccines that are going to expire could be transferred so that they are used rather than wasted. Vaccines are good until the last day of the month marked on the vial. They may be used until that date, unless otherwise indicated.
This article has provided the pediatrician with a few suggestions for handling vaccines. Additional information may be obtained from the Centers for Disease Control and Prevention, National Immunization Program, Atlanta, Georgia. Educational materials, including Vaccine Management: Recommendations for Handling and Storage of Selected Biologicals, Guidelines for Vaccine Packing and Shipping, and other publications from the Centers for Disease Control and Prevention, can be obtained at www.cdc.gov/nip/publications.
1. Centers for Disease Control and Prevention. Report No. 94, 1991-1995: Biologies Surveillance. Atlanta, GA: Centers for Disease Control and Prevention; 1997.
2. Brayden R, France EK. Efficient vaccination practices. Pediatr Ann. 2001;30:284-288.