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How Storage Temperature Impacts Vaccine Degradation

Posted on Oct 17, 2019 by Alex Evans

How Storage Temperature Impacts Vaccine Degradation


In this blog post, Alex Evans, PharmD, CGP, from Pharmaceutical Compliance gives us an important look into the impace of vaccine storage temperatures.

An often neglected but extremely important part of the pharmacy is the medical-grade refrigerator. It is used to store your vaccines and refrigerated medications and has a lot on its plate: if it goes down, or even fluctuates by a few extra degrees, the pharmacy could lose thousands.

When I'm walking by a pharmacy (or walking into a doctor's office, for that matter) one of the first things I notice is the type of refrigerator they are using, and more often than not, it is an off-the-shelf model from the local hardware store. In the past, I've been told by the company I worked for that they were going to purchase the "cheapest, no-frills refrigerator we can get" so they can get "my refrigerator problem solved quickly." After $25,000 in losses from temperature excursions they sent me a medical-grade refrigerator.

I think the main reason for the initial resistance is the price tag. Per square foot of space, a medical-grade refrigerator costs significantly more than a household model. Comparing these two units is like comparing the cost per square foot of seat space in your four-cylinder beater versus a brand-new Ferrari. It takes no consideration to what is under the hood.

This article is about what is under the hood of a medical refrigerator and why you need one:

temperature stability, uniformity & recovery

One of the most important features of a medical-grade refrigerator is their ability to maintain uniform temperatures across the cabinet. They use a forced-air circulation system that is designed, for pharmacy applications, to maintain  extremely tight uniformity, often within +/- 1.5 degree C. They can also return quickly to set temperature after the door is opened.

The graph below shows before (household) and after (medical-grade) temperature over time with regular usage. It is easy to see the difference in temperature stability between the two units.          

Household to Helmer Temp Data

Consumer models have so much cabinet temperature variation (especially dorm units, which should never be used, and refrigerator/freezer combination units) that you can have one section of the refrigerator, like the middle shelf, in range, and the back or the top of the refrigerator way out of range.

When comparing temperature fluctuations of a medical refrigerator and consumer model, there is a large difference in uniformity, recovery and stability. With the household unit, even if you set the temperature right in the middle at 40F you are going to get close to the top and bottom of the acceptable range (Per CDC: 36-46F) in certain areas of the cabinet putting you at a real risk for temperature excursions.


Thermostat controlled

There's nothing worse than having to try to barely turn the knob of a consumer refrigerator by even a millimeter to get the temperature just right. Not only will it take longer to set it at the correct temperature, but it is also riskier because if someone even slightly bumps the knob it could cause a big temperature change. Anytime I’ve been stuck with consumer models it has been a nightmare getting the temperature set.

Medical refrigerators have a built-in thermostat with microprocessor controls so you can set it at 40 degrees Fahrenheit and forget it. Not only will that mean it is easier, but you can get your product in it faster; the CDC recommends 2-7 days to be sure you are at a stable temperature, and with consumer models it has taken me at least 7 days, because the first few days were wasted trying to get the knob to exactly the right point to make it 40F.

Door alarms

One night, when I was finishing up a shift filling in at another pharmacy, I went to check our small freezer where we kept the Zostavax and found out the door had been cracked for hours. The temperature was in the 50s (Fahrenheit)! I called the manager of that store later and she said, 'Oh yeah with that freezer you have to be careful because the door will pop back open like that.'

Thankfully, in this case, Merck was able to provide off-label data to support its continued use, but you might not be so lucky.

All high quality medical-grade refrigerators are setup with door alarms to go off if it is cracked for any period of time, preventing this from .


Self-closing door design

If I had a door open alarm and a freezer with a self-closing door design, the Zostavax would never of experienced an excursion. This is a simple but important feature to look for.I have seen more than one occasion where a door was left open by mistake.Medical-grade refrigerator doors are designed to close automatically.


Glass front

It’s a small thing, but glass fronts allow you to see what you have in stock and where to get it from prior to opening the door, minimizing the amount of times the door is open.

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The bottom line

Remember, the refrigerator is an investment and it is there to protect medications that cost much more than the refrigerator ever will. If your pharmacy loses even a couple boxes of Prevnar or iPR120GX-125GX-CiLR105-GX-with-vaccine-C.pngUSEHumira to an excursion from a home model the medical-grade refrigerator would have already paid for itself. Medical-grade refrigerators are purpose-built for the storage of medications and come with numerous features not available in consumer models. In addition, there are a lot of sizes available to fit your needs. Every pharmacy, clinic, and lab should invest in one. Not only is your revenue at stake, but so is patient safety.

Medical refrigerators are available in sizes ranging from the ‘dorm-style’ (although it is definitely NOT a dorm refrigerator) to full-size models for larger pharmacies and clinics.


This post originally appeared on www.pharmcompliance.com.

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Alex Evans

Written by Alex Evans

Alex Evans, PharmD, CGP, is the Pharmacy Manager at Seton Outpatient Pharmacy in Jacksonville, Florida, and preceptor for the University of Florida and Florida AM University.

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