by Drew Buskirk, Senior Product Manager, Thermo Fisher Scientific
The past two years have seen vaccines take center stage in the public health conversation — but successful vaccination isn’t just about the medicine itself, but also how vaccines are stored and handled, which begins with an effective vaccine cold chain. The cold chain aims to keep vaccines within World Health Organization-recommended temperature ranges, from the point of manufacture to the point of administration. As part of the process, choosing the appropriate vaccine storage unit is vital to ensuring the vaccine remains potent through its journey to the patient.
Less than two years ago, commercial mRNA vaccines didn’t exist, nor did any protocols for vaccine storage and maintenance of this new modality. As experts anticipate more vaccine-preventable infections, learning how to store temperature-sensitive medicines correctly and efficiently will be key; even the slightest issue with temperature control can compromise their life saving qualities.
The emergence of new standards
Until recently, there were no standardized requirements for vaccine storage equipment. Every year, more than 50% of vaccines may be wasted around the world because of logistics issues and the exposure of vaccines to inappropriate storage temperatures, according to estimates from the World Health Organization. To remedy this waste, the U.S. Centers for Disease Control and Prevention’s (CDC) published recommendations in the Vaccine Storage and Handling Toolkit, and it’s updated yearly. It provides best practices on handling vaccines and recommendations on the cold chain. But this, on its own, is insufficient.
Enter the novel 2021 standards published by the vaccine storage committee of NSF International, formerly known as the National Sanitation Foundation, collected in the NSF 456–Vaccine Storage. A multi-institution committee of industry experts drafted this guidebook using data analysis modeled on real-life usage within clinics. It clearly defines a set of standards for vaccine refrigerators and freezers, with particular attention to maintenance of proper temperature ranges to verify vaccine efficacy, going beyond meeting the standards of generalized refrigerator and freezer laboratory equipment outlined in the UL 61010-2-011 or UL 471.
Key considerations for selecting equipment
Many equipment options offered today are not up to the latest standards, nor are they purpose-built for the storage of temperature-sensitive laboratory products or vaccines. This makes it difficult for labs to select cold storage solutions with confidence. For due diligence, it’s wise to request technical data sheets for the cold-storage equipment as well as ask the key questions below.
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How much of the unit is usable, and is it within standard range?
Just because a space within the cabinet is empty doesn’t mean it’s usable. Requesting guidelines for the allowable usable space within the cabinet helps mitigate risk of storing materials in the cabinet where the temperature is outside the required range due to air circulation within the unit. Additionally, when stocking the unit, make sure to consolidate the cargo for optimal performance.
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What is the average cabinet temperature, and what is the variation?
There is a wide variety of lab refrigerators available based on specific research needs. The COVID-19 pandemic increased the use of some of the lowest temperature solutions – around -70°C – but other equipment for cryopreservation, biobanking, or medication storage may be much higher. One element to consider, therefore, is overall temperature of the storage cabinet and temperature stability. It’s prudent to ask about the difference between the highest and lowest temperatures the unit reaches during the refrigeration or freezing run. Variation should be minimal.
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Is the temperature uniform across the refrigerator or freezer?
Temperature uniformity ensures there are no discrepancies, regardless of whether the medicine vial is at the front or the back of the cold storage cabinet. If the unit isn’t purpose-built, it’s likely to have poorer temperature uniformity. As recent research shows, most units went below freezing temperatures when they weren’t supposed to and pockets of the cabinet were vulnerable to higher-than-recommended temperatures with cold air displacement.
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Will the temperature recover quickly enough after opening cabinet doors?
Not only must the temperature remain the same over time and across the unit, but it must also account for routine door openings in clinics, hospitals or pharmacies. According to NSF standards, the rate of recovery for refrigerators must be between 2 and 8°C and between -50°C and -15°C for freezers within 15 minutes after prolong door openings. In cases of frequent and repeated use of the cabinet, purpose-built auto-defrost and frost-free freezers with more consistent temperatures are recommended.
Optimizing cold storage equipment
Once the unit is equipped for usage, according to the manufacturer’s recommendations, it may be necessary to invest in a temperature monitoring device. The device recommended by the latest regulatory standards is a digital data logger (DDL) which offers labs added peace of mind.
The right DDL will provide temperature measurements, have an alarm for out-of-range temperatures and use a detachable probe that can mimic the temperature for the vaccine vial, not just the unit — so it might be buffered with glycol, or sand. Keep in mind, this device must be maintained and calibrated routinely for optimal performance.
With these key considerations in mind, labs can be confident that vaccines are being stored according to the latest standards and they are contributing to an effective vaccine cold chain process that helps maintain the efficacy of the vaccine.
References
About the Author: Drew Buskirk, Senior Product Manager, Thermo Fisher Scientific, has over 12 years of commercial and management experience in the manufacturing and life science industry and is passionate about supporting and advancing researchers’ goals. Over the last 8 years, he has held multiple roles supporting life science equipment with a focus on cold storage.