Heath departments, hospitals, pharmacies, and vaccination and distribution centers face myriad challenges when deploying last-mile, cold-storage infrastructure for COVID-19 vaccines. The vaccines require deep-frozen storage — temperatures of -70^oC (-95^oF) in ultra-low temperature (ULT) freezers.

The availability of ULT freezers and cold-storage infrastructure provides the means to significantly reduce development time for therapeutics and vaccines because temperature stability testing at warmer temperatures (4^oC or -20^oC) is not needed prior to commercial release. However, major issues arise because many vaccination sites with new ULT freezers do not have the experience to install or maintain this type of equipment. As has been often reported, ULT freezer failures involving COVID vaccines are common because of the high levels of energy and mechanical stress required places significant stress on freezer componentry, such as compressors.

ULT freezers are considered mission-critical equipment, but they require close supervision. A failure can lead to the loss of high-value products and research specimens, as well as safety issues. Manufacturers and operators of large fleets undertake extraordinary measures to maintain them. First, most ULT manufacturers have their units tested for electrical and mechanical safety by a third party. 

Because ULT freezers put off large amounts of heat, they require adequate air flow around the unit involving special installation needs. This usually means the unit must be installed several inches away from the wall and that the facility HVAC system is enabled to handle large HVAC loads in areas where many ULT freezers are co-located. In addition, ULT freezers normally require dedicated electrical wiring and a separate circuit breaker.

Proper training and availability of personal protective equipment is crucial to ensuring user safety. ULT freezers are cold enough to cause frostbite, so users must wear insulated gloves when working inside the cabinet.

Finally, when the storage of FDA-regulated biologics is involved, industry standards and best-practices must be deployed including referencing good practice, or GxP, standards and protocols. When GxP is applied to a ULT, regulations require that the temperature variation in the storage cabinet be within +/- 10^oC of the targeted setpoint and that this be proven via recorded pre- and post-installation tests called validation. Compliance is accomplished using an independent temperature monitoring system, which also must be validated.

Yet, despite all of these efforts, there’s still a high failure rate. When failures occur, remediation is often too little, too late. However, recent advancements in monitoring systems leverage predictive analytics, shifting from the traditional fail-and-fix to new predict-and-prevent maintenance practices. These systems use machine learning to predict asset failures before they occur:

• Sample protection. Advanced machine health warning and cloud-based systems offer extra layers of assurance. With predictive analytics, the onset of mechanical stress leading to compressor failure can be detected, often days, weeks or sometimes months before a problem results in a breakdown which historically was only detected after temperature alarms fired.
• Increased asset service life. Addressing maintenance issues early can help increase asset life, typically two years for a 10-year asset.
• Energy savings. ULT freezer consume about 20 kWh/day, which is the equivalent of the energy consumed by an average house. Poorly maintained ULT freezers use more energy, however, predict-and-prevent monitoring systems identify poorly running units, which can be repaired or replaced to restore energy performance to known levels of efficiency.
• Emergency response repairs. Unplanned maintenance events that occur outside of business hours are not only expensive, but can result in a higher rate of product loss. Monitoring systems can preemptively indicate or tag poorly running units, allowing the operators to schedule them for service at a lower cost than an emergency repair.
• Global sourcing and purchasing intelligence. The capabilities of some systems include benchmarking techniques that enable the comparison of different brands for energy efficiency, cooling capacity and stability.

Despite having best practices in place to eliminate and reduce freezer issues, emergency plans are crucial. No system will identify every failure. A reliable source of dry ice and having coolers to take the inventory of a failing unit is a good start. In larger facilities, it’s also helpful to have back-up units.

ULT freezers are part of our medical infrastructure, helping to bring needed therapeutics to market in record time. They can also be effectively managed with predictive monitoring to save users time; money; and, most importantly, vaccines vital to human health.