Among the numerous logistical challenges to providing COVID-19 vaccines around the globe, temperature is receiving little attention. Relatively few logistics or healthcare organizations have freezers capable of cooling down to –80° C (–112° F). But vaccines using gene-based technology known as messenger RNA (mRNA) require such ultralow temperatures.

Against that backdrop, Stirling Ultracold has announced that its freezers for life science applications can store any COVID-19 vaccine candidate needing ultra-low temperature (ULT) storage for last-mile delivery. Vaccine candidates from companies such as Pfizer (NYSE:PFE) and Moderna (NSDQ:MRNA) have storage temperature requirements ranging from –20° to –80° C.

Relatively few companies make freezers that can cool down to –80° C. Ultra-low freezer competitors to Stirling Ultracold include Thermofisher Scientific, NuAire and K2 Scientific.

Ultra-cold-chain logistics

Vaccines require unbroken and accurate refrigeration to remain potent and safe. Yet almost 3 billion people across the world live in areas where temperature-controlled storage is inadequate to support wide-scale COVID-19 vaccination, according to a report by the Associated Press.

Cold-chain problems often stymie vaccination efforts. And as vaccine makers work to prioritize speed to market, their ability to perform stability testing over a range of temperatures is diminished. “That, of course, puts a lot more pressure on the requirements associated with ultra-low cold temperature requirements,” said Dusty Tenney, CEO of Stirling Ultracold.

The COVID-19 vaccine candidates have much colder temperature requirements than traditional vaccines. Routinely recommended vaccines, for instance, should be stored between 2° and 8°C, according to a CDC guide.

There are a half dozen vaccine candidates in Operation Warp Speed, the public-private partnership focused on COVID-19 vaccines, therapeutics and diagnostics. The total number of vaccines currently in development around the world is around 50, according to RAPS.

A range of requirements

Many of the vaccines that have clear potential for commercialization require storage in the range of –20° to –80° C. Vaccine candidates from AstraZeneca and Johnson & Johnson could potentially be stored between 2° to 8° C, according to a report by the Telegraph. mRNA vaccines, such as those Pfizer and Moderna are developing, require colder storage temperatures.

Few care providers have experience storing vaccines at übercold temperatures, said Robin Grimwood, president and chief operating officer, Infinity Biologix. For one thing, there is little need. Flu vaccines, for example, are refrigerated. The relatively few vaccines that are stored at frozen temperatures are commonly held at –15° to –50°C.

“Clinics or local hospitals may have –20° C capabilities, but they’re just not used to storing at –80° C,” Grimwood said.

Few developing countries have the infrastructure to ensure COVID-19 vaccines are stored at the appropriate temperature.

“Ebola provided a big example of some of the challenges of getting vaccines to remote areas,” Tenney said.

Stirling Ultracold is working to alleviate such problems by offering a standardized power port that can be used while vaccines are in transit. “In addition to that, we have a battery technology, and we are developing an application to use solar panels,” he added.

Traditional strategies to enable ultra-low temperature storage are to rely on dry ice or liquid nitrogen. Both require special handling. When used in closed areas, both dry ice and liquid nitrogen can cause asphyxiation.

“The real challenge from the last-mile perspective is, how do you get it out of the distribution hub down to the clinics and pharmacies that in a traditional world don’t necessarily deal with that level of infrastructure?” Tenney said.

Yet ensuring that vaccines are stored at the correct temperature is one factor needed to shore up public support for vaccines. Effective cold-chain logistics is vital to ensure vaccines are effective and win public support. Currently, less than half of the U.S. public would be willing to take a hypothetical COVID-19 vaccine with 50% efficacy. Widespread logistical cold-chain problems could further undermine public trust, Tenney said. If a COVID-19 vaccine “doesn’t have the desired impact, you’re going to have a world that’s just questioning the validity of the vaccine, which is the last thing that needs to take place,” he said.