Storing Refrigerated & Frozen Vaccines

Vaccines elicit an immune response to viruses and diseases, saving patients' lives and preventing serious illness. Failure to store them properly, though, can reduce and even eliminate their effectiveness.

This article will focus on vaccine storage guidelines, requirements, recommendations, and best practices as they relate to healthcare facilities and help operators find the best vaccine refrigerator. Consult the Centers for Disease Control and Prevention (CDC) or your local health department for additional information related to reception, transport, and preparation for use.

The CDC refers to vaccines as either public or private and recommends separating the two types in storage. Public vaccines in the United States are part of the government-sponsored Vaccines for Children (VFC) program, which uses public funds to provide immunizations at no cost to children that meet certain eligibility requirements. VFC providers exist to issue guidance on a state or local level and have specific storage and handling requirements that may differ slightly from each other.

The CDC offers general recommendations for storage and handling of private vaccines and gives additional information on best practices. This information also generally applies to public vaccines, but healthcare providers storing these should consult their local VFC program to ensure they meet location-specific requirements, which may be more stringent.

Vaccine Storage Guidelines & the Cold Chain

From the moment they're manufactured to the moment they're administered to patients, vaccines should exist in a cold chain that keeps them away from light and within their required temperature range. Each phase of vaccine storage and transportation represents an equally important link in the chain, including refrigerated and frozen storage at the end of the chain.

In the event of a temperature excursion or fluctuation outside the recommended range, the chain has been broken and action should be taken. Here are the requirements for maintaining the cold chain in refrigerated and frozen vaccines:

Refrigerated vaccines should be stored at temperatures between 36 and 46 degrees Fahrenheit, with the ideal temperature being 40 degrees Fahrenheit. VFC freezer requirements specify frozen vaccines should be kept between -58 and 5 degrees Fahrenheit. Keep freezer thermostats at their midpoint or factory setting to avoid a out-of-range temperatures in either direction. With the exception of MMR vaccine storage, vaccines require only refrigerated or frozen storage and can't be stored interchangeably.

For optimal equipment operation, ambient room temperature should be between 68 and 77 degrees Fahrenheit.

Equally important to the cold chain is preventing light exposure for certain vaccines. Vaccines should be stored and transferred in their original boxes with the lids closed.

Monitoring Temperature

Monitoring temperatures is an essential aspect to maintaining the cold chain. To monitor and record vaccine temperatures properly, operators need a temperature monitoring device, or TMD. At bare minimum, a TMD gives an accurate reading of temperatures, with the next level of functionality being a maximum and minimum temperature reading since the last time the unit was reset. These units may include probes buffered by glycol or another solution to emulate the temperature of stored vaccines closely and not just the air temperature. The thermostatic controls on most refrigerators and freezers measure levels of coldness instead of actual temperatures and therefore aren't adequate. Follow these steps to monitor and record temperatures using a TMD:

1. At the beginning of every workday, check and record the minimum and maximum temperatures since you last reset the TMD.
2. Reset the TMD.
3. Check and record the current temperature each time you access the unit throughout the day.
4. If your unit or recording device doesn't record minimum and maximum temperatures, check and record the temperature at the start and end of the workday and each time the unit is accessed.

Record data on a log sheet placed on or nearby the unit's door. Include the date and time, name of the person who recorded the data, and any actions taken. When using a new unit, record two consecutive days of stable, within-range temperatures before storing vaccines.

Digital data loggers, a type of TMD that automatically records temperatures for access from a computer or other device, reduce employee labor when checking temperatures. The CDC recommends devices with buffered probes, temperature and low-battery alarms, uncertainty of less than 1 degree Fahrenheit, and the ability to record at least every 30 minutes. Use of foodservice monitors and loggers isn't recommended.

Purpose-built units include digital data-logging features, microprocessor-based temperature control prebuilt into the unit, and forced-air circulation. The CDC doesn't require these special purpose-built refrigerators for storing and monitoring and doesn't endorse any units as meeting requirements, but it does recommend them. Other features to look for in these units are buffered probe thermometers, alarms, forced-air circulation, and locking doors.

Can I Use A Household-grade Unit?

Because refrigerated and frozen vaccines must be kept in a specific temperature range to maintain their viability, the best way to ensure consistent, proper temperatures is to use a medical-grade unit that's built specifically for storing vaccines. Household-grade refrigerators and freezers, though, can be a viable alternative as long as temperatures are monitored and consistently stay within range.

The CDC's vaccine storage guidelines advise a freestanding freezer or stand-alone refrigerator for vaccine storage. As a last resort, operators can use a household-grade combination unit for refrigerated vaccines only, provided the refrigerator and freezer are separated. Operators should never store frozen vaccines in combination units or use any combination units with a single door. These dorm-style units should be avoided because lack of separation between the freezer and refrigerator leads to inconsistent temperatures.

If you choose to use a household-grade unit, the CDC recommends storing water bottles on the upper and lower shelves, and in any door compartments. These bottles help keep temperatures consistent by providing insulation.

Follow these best practices for storage in both household-grade and purpose-built units:

• Keep vaccines in trays or containers that enable airflow, with VFC and private vaccines kept separate.
• Place vaccines that are set to expire first at the front of the refrigerator.
• Don't store any food or drink products other than water bottles. If water bottles are used, label them "do not drink."
• If it's necessary to store them in the same unit, place any biological products below vaccines to avoid potential contamination from drips and spills.
• Leave a few inches between vaccines and the refrigerator or freezer walls if water bottles aren't used.
• Purchase a unit with adequate space for all potential inventory.
• Post signage in appropriate areas that reads "do not unplug" and "do not change temperature."
• Inform and train all staff of vaccine storage guidelines.

Temperature Excursions

The CDC refers to an out of range temperature that occurs for any period of time as a temperature excursion. If this happens don’t throw away affected vaccines, but label them "do not use" and contact your local VFC program or private vaccine manufacturer for guidance. Follow the same steps if vaccines have been inappropriately exposed to light. Vaccines that have undergone a temperature fluctuation or exposure to light may still be usable with a revised expiration date.

Resources & Additional Info

1. Vaccine Storage and Handling Resources. Centers for Disease Control and Prevention. Accessed September 2020.
2. Vaccine Storage and Handling Toolkit. Centers for Disease Control and Prevention. Accessed September 2020.
3. Vaccines for Children Program (VFC) Contacts. Centers for Disease Control and Prevention. Accessed September 2020.