We brrr-ing you inside an ultra-cold freezer, the super-chilled home of the COVID-19 vaccine


They keep vaccines at sub-arctic temperatures. But what happens if regular stuff gets that cold? 3:30

Inside your freezer at home, it’s about as cold as a normal winter day in Canada. Inside an ultra-low-temperature freezer, it’s colder than Antarctica.

When you open the door of the latter, clouds of cold air billow out like fog. If you touch the inside with your bare hand, it will stick like Ralphie’s tongue to that frozen pole in A Christmas Story. And if you fill it with the kind of stuff that goes in your fridge, like fruits, veggies and kids’ snacks… let’s just say they become very fragile.

When things get really cold, they become hard and brittle. For example, this Wagon Wheel is normally soft and mushy. But after four hours in an ultra-low-temperature freezer, it smashes like glass. (Zach Goudie/CBC)

Ultra-low-temperature freezers have long been standard equipment in medical laboratories. But they’re suddenly a hot topic of interest, thanks to their vital role in rolling out vaccines for COVID-19.

In the faculty of medicine at Memorial University in St. John’s, a few dozen ultra-low-temperature freezers are in use for ongoing research. To protect the integrity of the substances inside, the freezers are kept in areas off-limits to the public, electronically monitored at all times for even the slightest rise in temperature. 

But the team at the faculty of medicine granted CBC News access to a freezer that had been emptied and decontaminated, so we could give you a look inside and answer some common questions about this very cool piece of equipment.

An ultra-low-temperature freezer doesn’t look particularly special. But inside, it can get colder than Antarctica. The gauge on this one shows a temperature of –61 C. (Zach Goudie)

How cold does it get?

An ultra-low-temperature freezer can go all the way down to –90 C. How cold is that? It’s colder than what a penguin in Antarctica is standing in right now. It’s about as cold as the coldest temperature ever recorded on Earth.

Dr. Patricia Cousins, manager of medical laboratories at the faculty of medicine, gave us another way to think about it.

“We’re standing in a hallway right now where it’s about 20 degrees Celsius,” said Cousins. “Minus-80 is 100 degrees colder than that. So if you can equate the difference between boiling water and freezing water, that’s the difference between the air inside that freezer and the air we’re breathing now.”

Dr. Patricia Cousins, manager of medical laboratories in Memorial University’s faculty of medicine, stands next to an ultra-low-temperature freezer, one of a few dozen at MUN. (Zach Goudie/CBC)

Why do some things (like vaccines) need to be kept so cold?

The Pfizer-BioNTech vaccine needs to be stored at around –80 C. (Moderna’s vaccine only needs to be stored at around –20 C.) But the actual freezing point of the Pfizer vaccine isn’t anywhere near that cold. So why do some things need to be more frozen than frozen? Cousins has the answer.

“Frozen is not necessarily frozen. We have different degrees,” she said. “Things like mRNA, for example, that everybody knows about because of the Pfizer vaccine and the Moderna vaccine, those things are very small stretches of nucleic acids, and they’re not super-coiled or twisted around each other like DNA. So those items are very prone to degrade.”

This is the view through Dr. Rod Russell’s microscope. Russell is a professor of virology and immunology at Memorial University’s faculty of medicine. (Zach Goudie/CBC)

Dr. Rod Russell, a professor of virology and immunology at the faculty of medicine, uses ultra-low-temperature freezers every day in his research. He says the same principle applies not just to vaccines but to all sorts of delicate substances, from tissue samples to enzymes.

“Some things need to be stored colder than others, because basically they’re less stable,” he said. “Molecules vibrate, and the more they’re vibrating, the more they can degrade. So if you can get them down to minus-50, minus-60, minus-80, they’ll preserve longer.”

Is the COVID-19 vaccine cold when they inject you with it?

Cousins and Russell get this question all the time. Some people are concerned that getting Pfizer’s COVID-19 vaccine will feel like an injection of ice water, having been stored in an ultra-low-temperature freezer. 

If your teeth have been chattering in anticipation, fear not: vaccines stored in these freezers are thawed at regular refrigeration temperatures and warmed to room temperature before they’re administered.

What happens to regular stuff if it gets that cold?

When not being used to store vaccines, ultra-low-temperature freezers are typically packed with medical samples and substances with unpronounceable names. But what happens if you fill one with stuff from a regular refrigerator?

We tested objects from a regular fridge inside an ultra-low-temperature freezer, such as this tomato. Needless to say, our experiment was a smashing success. (Zach Goudie/CBC)

“If regular objects are chilled that cold, depending on the composition of the object, it can do different things,” said Russell. “Things do get more brittle, more breakable, as they get colder and colder.”

In the name of science, we put a tray of fruits, vegetables and kid snacks inside the freezer for four hours. Then we tested how brittle those objects became through rigorous experimentation. 

Needless to say, the experiment was a smashing success.

WATCH | See our smashing experiment and learn more about ultra-low-temperature freezers:

They keep vaccines at sub-arctic temperatures. But what happens if regular stuff gets that cold? 3:30

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