Four Ways to Properly Store Vaccines

Every year, healthcare providers dispose of millions of dollars of stored vaccines when those vaccines become too warm or too cold.

However, researchers at the National Institute of Standards and Technology (NIST) in Gaithersburg, MD—with funding assistance from the Centers for Disease Control and Prevention (CDC)—recently completed the first of a series of tests to find out the best practices for properly storing and monitoring refrigerated vaccines.

These initial findings will be included in a CDC training video and report scheduled for July. To ensure they are effective, most vaccines must be kept between 2 and 8 degrees Celsius—from the time they are manufactured until they are administered, the researchers said.

In the first study phase, NIST researchers compared standard sized refrigerators without freezers against smaller, dormitory style refrigerators. They used a variety of conditions, storage practices, and use scenarios—including leaving the refrigerator door ajar for various periods, power loss, and raising the ambient temperature of the room.

The NIST Thermometry group found that standard sized, freezerless refrigerators always performed better than the smaller, dormitory-type refrigerators by every measure. But, the study also identified several good practices for vaccine storage:

• Vaccines should never be kept on the refrigerator door shelves because the lack of insulation in the door allowed unacceptable temperature drifts.
• Vaccines also should be kept away from the walls of the refrigerator because the defrost cycle could cause the temperature of the walls to shift.
• Vaccines should never be placed in crisper drawers, which are usually found at the bottom of standard refrigerators, because these areas are often shown to drop below 2 degrees Celsius.
• Water bottles kept on the door shelves provided "thermal ballast," which helps slow temperature rises in the event of power failures, leaving the door ajar, or raising the temperature of the room where the refrigerator is kept.

According to a NIST study, vaccines that have not been removed from their packaging—usually a cardboard box—retain their temperatures longer than those that have been unpacked and placed in trays. The standard sized refrigerators' ability to keep proper temperature was unaffected by how much vaccine the researchers stored in the refrigerator—a characteristic usually not shared by the dormitory style refrigerators.

"While we don't advocate any particular brand of refrigerator, we can say that the standard sized freezerless refrigerators perform very well, but the dorm style refrigerators do not and should not be used for storing vaccines," said NIST physicist Gregory Strouse.

He added that the research showed that healthcare providers really do not need to spend "several thousand dollars on a pharmaceutical grade refrigerator simply for the purpose of storing vaccines."

The NIST group plans said it plans to perform further comparisons of standard sized refrigerators with freezers and pharmaceutical-grade refrigerators. It also will evaluate strategies for shipping vaccines overland.