Don’t Assume That Old Refrigerator Is Good Enough To Store Vaccines

Animal health products stored in a refrigerator.
Animal health products stored in a refrigerator.
(K. Scott Jensen, University of Idaho)

There is a scenario with used refrigerators that occurs routinely across farm country: The old refrigerator is pulled out of the family kitchen when a new and improved version is installed. The old appliance is then moved to a garage, machinery shed or barn and repurposed. It might be responsible now for chilling a variety of items ranging from pharmaceutical products to employee lunches.

That’s fine if the refrigerator is up to the task. But that’s often not the case, according to research conducted by Emmanuel Rollin, DVM and clinical associate professor, College of Veterinary Medicine at the University of Georgia*. 

“It might be OK to store a Coca-Cola, but I wouldn’t want to leave my sandwich in some of them,” he says.

Rollin and team evaluated the performance of 20 refrigerators during a five-month period from July through November 2021. While the bulk of the refrigerators were household appliances, mini-refrigerators and a couple of commercial grade refrigerators were also  evaluated.

“Our main objective for the study was to go out into the real world and see how vaccines and other refrigerated pharmaceuticals are actually being stored on the farm and whether they are staying at the temperature recommended on the product labels,” he says. 

To maintain product integrity in refrigeration, the recommended temperature interval (RTI) for most biologics, including vaccines, is between 35°F and 45°F, according to Grant Dewell, DVM, associate professor and beef Extension veterinarian, and Troy Brick, DVM, assistant professor of vet diagnostic and production animal medicine, Iowa State University.

Not Up To Snuff

During the study, Rollin and team recorded the internal temperature of each refrigerator every 10 minutes, using a data logging device to accomplish that [Specifically, an InTemp Bluetooth temperature with glycol bottle (VFC/CDC) Data Logger that retails for about $175. It’s available here: link] While only 20 refrigerators were in the study, the team collected about a million data points. 

As suspected, the team found refrigerator performance was subpar in many cases. Results showed that household refrigerators were outside the recommended temperature interval 37% of the time, mini-refrigerators 27% of the time and commercial refrigerators 2% of the time.

Rollin says he was surprised the mini refrigerators, like those found in dorm rooms, performed as well as they did. Not surprising was that commercial units scored the best in the evaluation process. 

“Because they’re designed for commercial spaces and have better quality components, they have a way to dial-in and maintain the temperature. They also may have fans to keep the air flowing to improve circulation and minimize hot and cold spots,” Rollin says.

Similar Findings Elsewhere
Rollin’s findings are much like those found by the University of Arkansas Cooperative Extension Service in a 2008 study**. It evaluated 191 refrigerators used by producers, retail stores and veterinary clinics. Data loggers were used to record temps at 10-minute intervals over 48 hours. 

Of 191 refrigerators tested, 76% were unacceptable for storing pharmaceuticals, because temperatures were not consistently maintained between 35°F and 45°F. 

Refrigerator type and age were not critical factors in performance. However, refrigerator location did matter. The refrigerators in barns maintained the coldest (often freezing) temperatures. Refrigerators located in temperature-controlled environments performed better. 

Rollin and team looked at similar factors:

They considered the location of the refrigerator and whether the temperature of the room affected its ability to cool products. The short answer in many cases was yes.

The cooling power or style of the refrigerator and its age were noted. 

Researchers inventoried the types of items that were kept in the refrigerator. “That was interesting,” Rollin says. “Some of the refrigerators were packed. We saw everything from $100 worth of (product) inventory up to $15,000 of inventory in the refrigerators.”

Factors Not Evaluated
Since the completion of the study, Rollin says the most common question he has received from people is whether the refrigerated vaccines and other products are any good, once they’ve been stored outside a manufacturer’s prescribed temperature range for any length of time.

Because the study didn’t address that particular question, the University of Georgia study has no specific insights to offer. 

“Every vaccine is different and has different adjuvants, so how far it can get away from the ideal temperature zone and for how long that can happen before impacting the product’s efficacy, we just don’t know that,” Rollin says.

Dewell and Brick say, in their experience, vaccines that have “undergone temperature cycles above or below the recommended storage temperature (over time) will have reduced efficacy and may be completely worthless due to deactivation.” They detail proper vaccine handling practices in this online article, Vaccines: Handle with Care

Where To From Here?
Rollin recommends that livestock producers along with their veterinarians consider how refrigerator performance on the farm can impact the efficacy of animal health products stored in them. Here are some of his recommendations next steps:

For existing refrigerators, set the refrigerator temperature correctly for the pharmaceutical products it contains, he advises. Use a data logging device for monitoring, if possible.

“Even a cheap $5 dial thermometer you can find in the cooking section at the grocery store is better than nothing,” he says. “It will give you the temperature at the specific time you check it.”

For between $20 and $30 Rollin says producers can purchase a digital thermometer, which can provide temperature highs and lows in the refrigerator over a 24-hour period.

If the producer is building a new office or farm building or has the resources, Rollin recommends purchasing and installing a commercial refrigerator.

Likewise, if financial resources are tight, producers can check with their veterinarian or product distributor to see if they will supply a thermometer, says Fred Gingrich, DVM and executive director of the American Association of Bovine Practitioners (AABP).

“When I was in practice I had these little USB data loggers I’d throw into clients’ fridges to monitor the temperature,” Gingrich recalls. 

Keep the refrigerator organized and manage the inventory. “We saw a lot of refrigerators where products were just piled into them along with human food and human drinks, too,” Rollin says. “Keeping the refrigerator organized is going to make it quicker for somebody to reach in and get what they need and close the door rather than having it open for 10 minutes while they’re looking for something.”

“Those are all things that veterinarians can do to help producers,” Rollin adds. “A lot of times we're selling these products and relying on them to work. So, I believe it's our role to help producers make sure that those products are actually able to have their intended use of preventing disease.”

Recently, Rollin spoke with Dr. Gingrich about the refrigerator study on a ‘Have You Herd’ podcast, which is available for free at You can access it here:


*Fallness, C. A., Rollin, E., Heins, B. D., & Berghaus, R. D. (2022). Maintenance of the last step of the cold chain: on-farm refrigerator storage and performance. The Bovine Practitioner, 56(2), 62–69.

**“The Temperature Variability of Refrigerators Storing Animal Health Products”, T.R.Troxel, PAS, B.L.Barham, PAS, University of Arkansas, Division of Animal Health, Cooperative Extension Service.


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