COVID-19

Some biological materials must be kept at cold temperatures because it stops ice crystals from increasing in size and thereby damaging cell membranes. Image: University of Ottawa/provided

A LOOK AT THE SCIENCE BEHIND WHY ONLY THE MODERNA VACCINE CAN BE SHIPPED TO REMOTE COMMUNITIES

On Feb. 1, Ornge, launched Operation Remote Immunity in partnership with Nishnawbe Aski Nation (NAN) to bring the COVID-19 Moderna vaccine to Indigenous communities in Northern Ontario. 

The non-for-profit “high quality air ambulance service” assists remote communities and aims to distribute Moderna’s COVID-19 vaccine to “31 northern, remote NAN communities and Moosonee over the next three months.” 

Recently, Ornge delivered and administered vaccines to residents of Slate Falls and Kashechewan First Nation among others.

Ornge is only delivering Moderna vaccines rather than the Pfizer-BioNTech vaccine as it is too difficult to ship. 

“We are only working with the Moderna vaccine at this time. And the reason why we’re using this vaccine is because it gives us a little bit more flexibility to transport”, said Robert Teranishi the logistics section chief for the project and a critical care paramedic with Ornge since 2006.

However, there are still challenges associated with the shipment of Moderna. 

“Our biggest challenge is to make sure that we can transport the vaccine as per the recommendations,” said Teranishi. 

“We are sometimes flying for as long as two hours to get to Northern communities, and sometimes we stay there overnight. So, the most important thing is to preserve the vaccine at a constant temperature.”

For example, vials must be kept at -20 C throughout the entire delivery. This means that Ornge’s healthcare workers cannot start the thawing process until [they] get to the clinic where it will be administered,” said Teranishi.

In comparison, according to Canada’s Ministry of Health guidelines, the Pfizer-BioNTech vaccine must be stored at -70 C to preserve its integrity.

Additionally, Teranishi said, “Moderna cannot be refrozen so we need to calculate how many vaccines each community needs to avoid wastage.”

“It is important that vaccines be preserved in a frozen state, this keeps it safe.”

Some biological materials must be kept at cold temperatures because it stops ice crystals from increasing in size and thereby damaging cell membranes. 

The science behind transporting biological materials

According to Robert Ben, a professor in the department of chemistry and biomolecular sciences at the University of Ottawa, some biological materials must be kept at cold temperatures to stop the expansion of ice crystals which damages cell membranes. 

In a press release by the U of O, Ben said, “some therapies such as vaccines need to be stored at very cold temperatures so they can be preserved for longer.” 

“For example, the Pfizer COVID-19 vaccine must be kept at -70 C to keep the ice crystals from growing too large and damaging the product.”

“Fragile biological materials are typically stored in sub-zero temperatures using a process called cryopreservation.”

“Crystals form inside the cells and around the cells. They’re everywhere within a frozen sample,” said Ben.  

During the warming process of frozen samples, or if the samples are not stored at cold enough temperatures, the crystals grow in size and this damages most of the cells.

“Cryopreservation’s dirty little secret is that, for one sample, we might only be able to recover 100 to 300 thousand cells out of the millions of cells that we initially freeze.”

Ben provided an analogy to illustrate the destructiveness of expanding crystals. 

“Imagine that you lay on a beach in the Caribbean. The sand conforms to your body and it’s comfortable.” This is the analogy for the small ice crystals. 

“Now imagine that you lay on a gravel driveway. It’s not so comfortable right?” This represents the destructive nature of large crystals that form during the warming process of a cryopreserved sample. 

Ben explained that with a new technology called recrystallization inhibitors prevents this sort of damage.

Ben and his team at the U of O developed a technology that prevents ice crystals from growing larger which could allow vaccines to be stored at much warmer temperatures. Called ‘ice recrystallization inhibitors,’ this technology keeps ice crystals small so that they do not damage cell membranes and could help future projects like those organized by Ornge

“Our technology can stop the expansion of ice crystals keeping them tiny which means that we can avoid cellular damage,” said Ben.

In the press release, Ben said that this technology stops all “cellular damage caused by ice. In the end, we recover more cells, they’re healthier and more functional.”

“This is an attractive technology for storage of cell, tissues and even vaccine conjugates which could be stored at -20 C instead of -80 C, to facilitate transport and distribution.”