Spotlight on CDC Recommendations for COVID-19 Vaccine Storage and Monitoring

In late November 2020, the Centers for Disease Control and Prevention (CDC) added a COVID-19 vaccine addendum to their Vaccine Storage and Handling Toolkit. Much of the addendum, such as staff and training guidelines, echoes what's in the main toolkit. However, it's worth highlighting the recommendations on vaccine storage and monitoring equipment, some of which apply specifically to COVID-19 vaccination programs.

Vaccine Storage Units

Units built expressly for storing medical treatments like vaccines and diluents often have special temperature controls, sensors, and air circulation mechanisms to maintain steady temperatures and recover quickly from out-of-range temperatures.

Refrigerators built for home use can also be used. However, the CDC says that "the freezer compartment of this type of unit is not recommended to store vaccines and there may be other areas of the refrigerated compartment that should be avoided as well. If your facility provides frozen vaccine, a separate freezer unit is necessary."                                                                                                      

Some COVID-19 vaccines, such as the Pfizer vaccine, must be shipped and stored at ultra-low temperatures. If a provider doesn't already have an ultra-cold freezer, the CDC doesn't recommend purchasing one since vaccines that require ultra-cold storage equipment will likely be shipped in compliant containers that can maintain ultra-low temperatures.

Digital Data Loggers

Each vaccine storage unit should have a temperature monitoring device (TMD) to detect whether vaccines are being kept within the required temperature range.

To get the most accurate temperature information about a storage unit, the CDC recommends a particular type of TMD known as a digital data logger (DDL). Some DDLs also use a buffered temperature probe to accurately measure the temperature of the vaccines themselves, not just the temperature inside the storage unit.

For their buffered temperature probes, compliant DDLs typically use pure propylene glycol (which freezes at -59°C/-74.2°F) or a glycol mixture with a warmer freezing point. DDLs for ultra-low freezers require an air probe or other purpose-built probe for ultra-cold temperatures.

Even with a TMD in place, healthcare staff needs to check storage unit temperatures at regular intervals. When using a DDL that measures minimum and maximum temperatures, those values only need to be checked and recorded at the beginning of the workday. If the DDL doesn't have that capability, temperatures should also be checked and recorded at the end of the workday.

Best Practices for Vaccine Storage

The CDC outlines best practices for storing COVID-19 vaccines to protect the vaccine, reduce the chance of errors, and ensure the most efficient operation of vaccine storage units:

• Using water bottles inside storage units to help keep temperatures constant
• Storing only vaccines, diluents, and water bottles inside units
• Keeping vaccines and diluents in their original packaging
• Leaving two to three inches of space around vaccines and diluents to allow for airflow
• Placing vaccines and diluents with the earliest expiration dates at the front

Note that EUA vaccine labels may not display expiration dates, and the dates may change as more data is collected. The CDC is developing a COVID-19 Vaccine Expiration Date Tracking Tool for its website.

Temperature Excursions

When a temperature excursion occurs, it's crucial to capture the details about when it happened and how long it lasted.

The vaccine manufacturer needs to know the date and length of the excursion, the storage unit temperature (minimum/maximum, if available), and the inventory affected to determine whether the vaccine within the storage unit is still viable. Since the manufacturer's response to the excursion depends on the healthcare provider's data, every effort should be made to supply complete and accurate data.

The CDC says that "each [excursion] event is unique, and [vaccine] manufacturer recommendations cannot be applied to future events that may appear to be similar. For COVID-19 vaccines, CDC will be providing manufacturer contact information to help address vaccine- and temperature-related questions." Healthcare providers who encounter a temperature excursion may also need to follow up with their storage unit supplier to understand why the excursion happened and to minimize future excursions.

Because the COVID-19 vaccination program will be large and swift, with patient health at stake, healthcare providers should get all the support available from suppliers to make sure they have the best storage and monitoring equipment possible and know how to use it correctly.