A South African company says it has the solution to a major headache around Pfizer’s coronavirus vaccine: keeping it cold.

The Pfizer shot has to be kept ultra-cold, which means airlines have had to be granted special permission to use large quantities of dry ice, while local companies with refrigerated transport capacity try to figure out how to get cold payloads to rural reaches.

But using the helium it produces in the Free State in a newly-patented container can keep vials of vaccine at -70 degrees Celsius for up to 30 days without the use of electricity, says listed company Renergen, “regardless of ambient conditions”.

The Renergen Cryo-Vacc can carry 100 doses of vaccine in a format that stacks, so that it can be used in traditional logistics chains, the company says.

Each aluminium container comes in at less than 20 kilograms, making it easy enough to lift, and the company says the cost per vial should come in at the equivalent of just over R1 per dose of vaccine.

Instead of using dry ice – or much heavier liquid nitrogen – the Renergen Cryo-Vacc contains a reservoir of liquid helium, which forms when helium gas is lowered to -269 °C. That is boiled and slowly released to maintain a constant temperature.

The same device can be used with liquid nitrogen too, the company says, but that cuts down on the time available for transport or increases weight: the vaccines must either be delivered without four days, or an extra 15kg must be added to each (normally sub-20-kilogram) container.

Renergen is now calling for partners “with the resources to roll-out large-scale manufacture” of the Cryo-Vacc, and global logistics companies to carry them.