Learn how to optimize the storing of vaccines to ensure CDC compliance.

Vaccines have eradicated and ameliorated some of the world’s deadliest diseases. Due to the vaccination efforts of the Global Polio Eradication Initiative, global incidences of polio have been reduced by 99% since 1988.1 Between 2000 and 2011, deaths from measles declined by 71 percent worldwide and by 80 percent in sub-Saharan Africa,2 a feat that would not have been accomplished without vaccines.

Proper storage is crucial to ensuring a vaccine’s efficacy. Exposure to suboptimal temperatures due to improper storage compromises vaccine potency and can result in an inadequate immune response in patients. Furthermore, reduced potency wastes products and inflicts significant financial losses on providers.

A 2012 Centers for Disease Control and Prevention (CDC) report revealed improper storage of some vaccines from the Vaccines for Children (VFC) program, which serves an estimated 40 million children through a national network.3 Though the health of the children was reportedly not compromised by the vaccines in question, the CDC and VFC providers have worked with a sense of urgency to ensure vaccines are stored according to requirements.

The CDC provides guidelines on best practices for vaccine storage partly based on studies conducted by the National Institute of Standards and Technology (NIST).4 The guidelines address myriad issues, from the grade and type of an acceptable storage unit to the proper configuration of components inside the unit. The CDC has also instructed immunization providers to consult package inserts for vaccine-specific storage guidelines. The inserts can be found at www.immunize.org/packageinserts.

Here are five key takeaways from the CDC’s vaccine storage guidelines to help immunization providers ensure compliance.

1. The CDC’s basic requirements for a vaccine storage unit.

According to the CDC, a vaccine storage unit should meet a few basic requirements:

  • Be a stand-alone unit, i.e., one that is self-contained and only capable of refrigerating or freezing. These units maintain set temperatures better than combination refrigerator/freezer units.5
  • Be capable of maintaining proper storage temperatures:

    • Stand-alone refrigerator: Between 35°F and 46°F (2°C and 8°C), set to achieve an average of 40°F (5°C).
    • Stand-alone freezer: Between -58°F and 5°F (-50°C and -15°C). A storage unit that is frost-free or has an automatic defrost cycle is preferred.
  • Have ample space to store the largest inventory a provider might have at the busiest point in the year, e.g., flu season, without crowding. 
  • Be monitored by a calibrated thermometer that came with a certificate of calibration.
  • Be pharmacy grade or purpose built. Pharmacy-grade and purpose-built refrigerators are specifically engineered to have uniform temperatures throughout. 

2. A household or dormitory style unit will not suffice for storing vaccines.

Most household combination refrigerator/freezer units operate with a single condenser and therefore are incapable of simultaneously maintaining proper storage temperatures in both compartments. This setup creates cold spots and temperature fluctuations in the refrigerator portion and increases the likelihood of freeze-damage because freezer air is circulated into the refrigerator for cooling.

Dormitory-style units should not be used under any circumstances. A NIST study showed that this type of unit demonstrated inconsistent temperature control, regardless of the vaccine's location in the unit. Within two weeks of use, the median temperature of the refrigerator set point had drifted approximately 4 °C lower, freezing the vaccines contained inside.5 Thus, this type of unit poses a significant risk of freezing a vaccine even when it is used for temporary storage.

3. The interior of the refrigerator or freezer requires special configuration.

A refrigerator or freezer used for vaccine storage should have the following configuration: 

  • Water bottles (refrigerator) and frozen coolant packs (freezer) placed in key areas in the unit. These help maintain stable temperatures and serve as a physical barrier from areas in the unit that pose a greater risk for temperature fluctuations. These risky spots are the top shelf, floor, and door racks in a refrigerator and along the walls, back, bottom, and door rack in a freezer.
  • A temperature-monitoring device placed near the vaccines. It is acceptable to monitor air temperature, but glycol probes give a better indication of actual sample temperature.
  • Storage bins placed in rows in the central area of the unit, at least two to three inches away from the walls. Vaccines and diluents should be sorted by type and a diluent must be stored with its corresponding vaccine when both have the same or similar storage temperatures.  

4. A stringent temperature monitoring protocol is recommended.

Routine storage and handling plans should include protocols for reviewing and recording storage unit temperature readings at the beginning and end of the day, and at least twice during the day. In the event of a mechanical malfunction or power outage, the date and time should be noted.

Use of a continuous monitoring device/digital data logger to record and store temperatures for 24-hour monitoring at regular intervals is recommended. The data logger should have a digital display attached to the outside of unit to allow measurement without opening the door and disturbing the probe. At least once a week, the data should be downloaded, reviewed, and stored as hard and digital copies. Logs should contain data from the last three years. 

5. Large vaccine storage facilities need back-up generators to ensure vaccine safety in the event of a power outage.

If a power outage is short-term (two hours or less) and the ambient temperature is normal, it is possible to maintain storage temperatures if the unit is stocked with water bottles (refrigerator) or frozen coolant packs (freezer) and the door is kept closed. In this case, it is paramount that the temperature inside the unit is closely monitored using an independent monitoring system that will continue to collect data despite the power outage, allowing the user to make an informed decision about sample integrity. Not all monitoring systems have this capability, so it is important to look for this feature when selecting a system.

Facilities storing large vaccine inventories should consider installing back-up generators that automatically provide power to storage units in the event of power outages. Back-up generators should have adequate fuel supply on hand and have sufficient capacity to run continuously for 72 hours. Back-up generators should also be tested quarterly and should receive maintenance at least annually.

Carl Radosevich ([email protected]) is a product specialist at Panasonic Healthcare Corporation of North America. To read more recommendations on vaccine preservation and cold storage, visit: http://us.panasonic-healthcare.com/business/healthcare/biomedical/vaccine/

1 History of Polio. (2010). The Global Polio Eradication Initiative. Retrieved from
2 Immunizations: Current Status and Progress. (2014). UNICEF. Retrieved from http://www.data.unicef.org/child-health/immunization
3 U.S. Department of Health and Human Services. (2012). Vaccines for Children Program: Vulnerabilities in Vaccine Management. Washington, DC: Levinson, D. Retrieved from http://oig.hhs.gov/oei/reports/oei-04-10-00430.asp
4 U.S. Center for Disease Control. (2014). CDC Vaccine Storage and Handling Toolkit. Atlanta, GA. Retrieved from http://www.cdc.gov/vaccines/recs/storage/toolkit/storage-handling-toolkit.pdf
5 U.S. National Institute of Standards and Technology. (2009). Thermal analysis of refrigeration systems used for vaccine storage. Gaithersburg, MD: Chojnacky, M., Miller, W., Ripple, D., & Strouse, G. Retrieved from http://www.nist.gov/customcf/get_pdf.cfm?pub_id=904574

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