Vaccine Storage Units

For Health Care Providers

What to know

Each facility should have proper storage equipment that is set up correctly, maintained appropriately, and repaired as needed.

Vaccine Storage Units: Refrigerator and Freezer

Dormitory-style Combined Units

Never use dormitory- or bar-style combined refrigerator/freezer units for vaccine storage. These units have a single exterior door and an evaporator plate/cooling coil, usually located in an icemaker/freezer compartment. These units pose a significant risk of freezing vaccines, even when used temporarily.

Not all small storage units are dormitory- or bar-style. Compact, purpose-built units for biologics are acceptable for vaccine storage.

Four types of units are suitable for storing vaccines and are listed below in order of preference.

1. Units that conform to National Sanitation Foundation/American National Standards Institute (NSF/ANSI) Standard 456

A unit that conforms to NSF/ANSI Standard 456 is preferred. These units can come in various forms and have been rigorously tested for vaccine stora

2. Purpose-built units

Purpose-built units are the next best option because they are specifically designed for vaccine storage. They can be compact, under-the-counter style, or large units, and are typically designed for either refrigerating or freezing vaccines; however, some units (i.e., combination units) are designed to do both. Additional information about purpose-built units can be found in the toolkit's Resources section.

3. Pharmaceutical-grade units

Pharmaceutical-grade units are the third best option because they are specifically engineered to store pharmaceuticals or biologics. These units often have

  • Microprocessor-based temperature control with a digital temperature sensor (thermocouple, resistance temperature detector [RTD], or thermistor), and
  • Fan-forced air circulation with powerful fans or multiple cool air vents that promote uniform temperature and fast temperature recovery from an out-of-range temperature.

4. Household-grade units (for vaccine refrigeration only)

Household-grade units may be used as a last option, but only for refrigerated vaccines. Never store vaccines in the freezer compartment of household-grade combination refrigerator/freezer units because they have cold spots and temperature fluctuations. If the facility stocks frozen vaccine, a separate stand-alone freezer unit is necessary.

Temperature variations can occur with the refrigerator compartment of a household-grade unit also. Air circulating from the freezer may expose refrigerated vaccines to freezing temperatures, so avoid storing vaccines on the top shelf directly under cooling vent. Do not turn off the freezer compartment, as this will prevent the refrigerator from maintaining proper temperatures. Avoid storing vaccines and diluents in any part of the unit that may not provide stable temperatures or sufficient air flow. These areas include directly under cooling vents; in deli, fruit, or vegetable drawers; or on refrigerator door shelves.

Best Practices for Using Water Bottles in a Household-grade Unit

  • Place water bottles on the top shelf, in the door racks, and on the unit floor of household-grade units. Doing so can help guard against temperature fluctuation caused by a power failure or frequent door opening and closing.
  • Water bottles are not recommended for use with the majority of pharmaceutical-grade and purpose-built units. For such units, follow the manufacturer's guidance.

☑ 🖍 Use units with enough space to accommodate the maximum inventory without crowding.

Crowding blocks cold air circulation, leading to temperature fluctuations that can compromise vaccine viability.

Storage Unit Placement

Good air circulation around the outside of the storage unit is essential. Always refer to the manufacturer-supplied owner’s manual for storage unit placement. In general, position the storage unit in a well-ventilated room, leaving at least 2 inches (5 cm) of clearance from the ceiling and 1 to 2 inches (2.5 to 5 cm) from any adjacent walls. The cover of the motor compartment should not be blocked. The unit should be level and stable, with the bottom of the unit 1 to 2 inches above the floor. The unit door should open and close smoothly, fitting squarely against the body of the unit. If not properly secured, unit doors can compromise the internal temperature of vaccine storage units. Studies have found that most units work best when placed in an area with standard indoor room temperatures, typically between 20°C and 25°C (68°F and 77°F).

Storage Unit Doors

A door that is not sealed properly or is left open not only affects the unit's temperature, but also exposes vaccines to light, which can reduce the potency of some vaccines. Consider using safeguards, such as self-closing door hinges, door alarms, or door locks, to ensure unit doors remain closed.

Stabilizing Temperatures in New and Repaired Units

It may take 2 to 7 days to stabilize the temperature in a newly installed or repaired refrigerator, and 2 to 3 days for a freezer. Before using a unit for vaccine storage, check and record the minimum and maximum temperatures each workday for 2 to 7 days. If temperatures cannot be recorded digitally, check and record temperatures at least twice each workday. After 2 consecutive days of temperatures recorded within the recommended range, the unit is considered stable and ready for use.

Temperature Ranges

☑ 🖍 Storage units must maintain the following temperature ranges at all times:

  • Refrigerators between 2°C and 8°C (36°F and 46°F)
  • Freezers between -50°C and -15°C (-58°F and +5°F)
  • Ultra-cold freezers between -90°C and -60°C (-130°F and -76°F)

Thermostats should be set at the factory-set or midpoint temperature—for example, 5°C (41°F) for refrigerators or -20°C (-4°F) for freezers—to help reduce the risk of temperature excursions. Consult the owner's manual for instructions on how to operate the thermostat. Thermostats are marked in various ways and, in general, show levels of coldness rather than temperatures. The only way to know the temperature of a vaccine storage unit is to measure and monitor it with a temperature monitoring device.

Temperature Ranges May Differ

Certain COVID-19, monkeypox, and RSV vaccines have specific temperature requirements for storage. For example, mResvia, an RSV vaccine, if stored frozen, must be stored at temperatures between -40°C and -15°C (-40°F and 5°F). This is a narrower range than many other frozen vaccines, which are stored between -50°C and -15°C. If you store mResvia alongside other frozen vaccines, ensure the storage unit temperature does not fall below -40°C. Always review the manufacturer's package insert or EUA Fact Sheet for Healthcare Providers to verify immunization product storage requirements and ensure that the correct temperature range is maintained.

Organizing and Storing Vaccines

Correct vaccine organization and placement helps prevent conditions that could reduce vaccine potency.

☑ Store vaccines in their original packaging, with lids closed, until ready for administration.

The original packaging for vials and manufacturer-filled syringes contains critical information, including product identification, storage requirements, and expiration dates. It also protects vaccines from light, which is essential for many products to maintain potency. Loose vials can also be confused with other vaccines, increasing the risk of inventory and administration errors. However, for certain purpose-built units, storing vaccines outside their original packaging is recommended. If this is the case, always follow the manufacturer's guidance for proper storage.

If vaccines must be removed from the original packaging (e.g., for transport to an off-site clinic or when moving doses from the freezer for thawing), protect them from light by using a resealable, opaque container such as an envelope, opaque plastic bag, or clear plastic bag lined with paper.

Best Practices for Vaccine Organization and Storage

  • Store each type of vaccine or diluent in its original packaging and in a separate container.
  • Position vaccines and diluents 2 to 3 inches from the unit walls, ceiling, floor, and door. If using a household-grade unit, avoid storing vaccines and diluents in any part of the unit that may not provide stable temperatures or sufficient air flow, such as directly under cooling vents; in deli, fruit, or vegetable drawers; or on refrigerator door shelves. The instability of temperatures and air flow in these areas may expose vaccines to inappropriate storage temperatures.
  • Label shelves and containers to clearly identify where each type of vaccine and diluent is stored.
  • Store vaccines and diluents with similar packaging or names, or with both pediatric and adult formulations, on different shelves.
  • Whenever possible, store diluent with its corresponding refrigerated vaccine. Never store diluent in a freezer.
  • Avoid placing or storing any items other than vaccines, diluents, and water bottles inside storage units. Never store food and beverages in the unit with vaccines. Frequent opening of the refrigerator door to retrieve food items can adversely affect the internal temperature of the unit and potentially damage the vaccines. If other medications and biological products must be stored in the same unit as vaccines, they must be clearly marked and stored in separate containers or bins.

    - Potentially contaminated items (e.g., blood, urine, stool) should be properly
    contained and stored below vaccines due to risk of contamination from
    drips or leaks.

    - The freezer of a household-grade unit may be used for non-vaccine
    medical storage, so long as the use does not compromise the temperature
    range within the refrigerator compartment.
  • To promote air circulation, arrange vaccines and diluents in rows and allow space between them.
  • Place vaccines and diluents with the earliest expiration dates in front of those with later dates.

Regular Maintenance of Vaccine Storage Units

Storage units and TMDs require regular maintenance to ensure proper operation and extend the useful life of the equipment. Check the manufacturer's product information for cleaning instructions and recommended maintenance schedules. Document maintenance tasks and repairs, as indicated in the facility's routine storage and handling plan and SOPs.

☑ Conduct routine maintenance on all vaccine storage units and related equipment to ensure they function at maximum efficiency.

  • Check seals and door hinges.
  • Clean coils and other components per the manufacturer's directions.
  • Manual-defrost freezers should be defrosted when the frost exceeds either 1 cm or the manufacturer's suggested limit. Follow the manufacturer's instructions. While defrosting, store vaccines temporarily in another unit with appropriate freezer temperatures.
  • Clean the interior of each unit as needed to discourage bacterial and fungal growth. Do so quickly to minimize the risk of a temperature excursion.
  • 🖍 Test any backup generator quarterly and have it serviced annually.

Troubleshooting Equipment Problems

Adjusting Storage Unit Temperatures

Adjusting Storage Unit Temperatures

If using a combination storage unit, note that adjustments to the freezer temperature can adversely affect the refrigerator compartment temperature, possibly resulting in frozen vaccines in the refrigerator.

Storage unit temperatures may need to be adjusted over time. In some situations, thermostats may need to be reset in summer and winter, depending on room temperature.

Temperature adjustments should be

  • Made by the primary or backup vaccine coordinator, based on information from the TMD and temperature monitoring log
  • Performed at a time when the unit door is not being frequently opened and closed

Remember that temperatures within any storage unit will vary slightly, even with normal use. Therefore, before making any adjustment

  • Confirm the unit is securely plugged into a power source.
  • Check the temperature inside the storage unit.
  • Wait 30 minutes without opening the door to allow the temperature to stabilize, and then recheck it to determine if the thermostat needs to be adjusted.

If there could be an issue with the TMD, use the backup device to confirm the temperature. After confirming that an adjustment is needed

  1. Refer to the owner's manual for detailed instructions.
  2. Make a slight adjustment toward a warmer or colder setting by turning the thermostat knob slowly to avoid going outside the correct temperature range.
  3. Once the adjustment is made, allow the temperature inside the unit to stabilize for 30 minutes without opening the door.
  4. Recheck the temperature.
  5. Repeat these steps as needed until the temperature has stabilized
    1. Between 2°C and 8°C (36°F and 46°F) for a refrigerator,
    2. Between -50°C and -15°C (-58°F and +5°F) for a freezer,
    3. Between -90°C and -60°C (-130°F and -76°F) for an ultra-cold freezer.
  6. If appropriate for the unit, consider adding extra water bottles to improve temperature stability.

☑ 🖍 Never leave vaccines in a storage unit that does not maintain temperatures within the recommended range. If the unit is unable to stabilize the temperature within the required range, or if temperatures in the unit consistently fall at the extreme high or low end of the range, the vaccine supply is at high risk of losing its potency. Refer to the facility's SOPs to identify an alternative unit with appropriate temperatures and sufficient storage space until the primary unit can be repaired or replaced.

VFC Reminder

VFC providers and others who administer vaccines purchased with public funds should contact their immunization program for state-specific requirements related to vaccine storage units.

Icon Guide

☑ CDC Guidance

🖍 VFC provider requirement

★ Best Practices

⚠︎ Important Reminders

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Content Source:
National Center for Immunization and Respiratory Diseases; Immunization Services Division