Covid-19 coronavirus: Super-cooling concerns over US, German vaccine contenders

Masks are the main form of protection for people until a successful vaccine is available. Photo / AP file

Two of the world's leading Covid-19 vaccine contenders may have to be stored at temperatures as low as -70C, it has emerged.

The super-cooling requirements for the leading US and German contenders adds another layer of complexity to the task of distributing the vaccines, even if phase three trials prove successful.

Most other leading candidates, including from Oxford/AstraZeneca, must also be kept cool, but there are hopes these protein-based jabs will need to be refrigerated at between 2C and 8C, rather than frozen.

Both Pfizer and Moderna are developing mRNA vaccines, with data signalling that they will need to be transported and stored at ultra-cold temperatures of -70C and -24C respectively to ensure their chemical structures remain stable.

If they become too warm for too long at any point along the "cold chain" - the journey from the point of manufacture to injection - they may be rendered ineffective.

Apparently the individual w/ the adverse event has a transverse myelitis, a neurologic condition which can result from infections or an immune system disorder. The adenovirus component of the vaccine may have been a trigger https://t.co/unZ03Ywq7E pic.twitter.com/oxhXXW5M7e

— Eric Topol (@EricTopol) September 9, 2020

"I can't emphasise enough the complexity of maintaining an absolute temperature from the depot to the surgery," said Nick Jackson, head of programmes and innovative technologies at the Coalition for Epidemic Preparedness Innovations.

"It's incredibly difficult even on a good day with vaccines that are refrigerated. But the challenges are made harder as you begin to lower the temperature requirements."

According to research by logistics firm DHL and consultancy McKinsey, at least two thirds of the world's population are unlikely to have easy access to any jab that needs to be maintained at sub-zero temperatures.

Katja Busch, DHL's chief commercial officer, told the Telegraph that she is unaware of distributing a human vaccine globally at below -70C.

"It's doable with a special package and dry ice," she said. "But the biggest question is what happens at the final, final mile, once the package has been dropped off."

Donald Trump, the US President, recently intimated that he would try and shortcut regulatory hurdles to license products ahead of the US presidential election on November 3.

Thus I'd rather emphasize the additive nature of risk reduction. For aerosols, droplets, or fomites, people should implement as many of the following measures as possible:
-Physical distance
-Avoid crowds
-Avoid indoors/enclosed spaces
-Masks
-Ventilate/filter
-Wash hands

— Dr. Angela Rasmussen (@angie_rasmussen) September 8, 2020

And Boris Johnson, the British Prime Minister, has hinted at a special fast-track licensing process.

But in an unprecedented move yesterday, nine leading vaccine developers - including Pfizer, Moderna, GlaxoSmithKline and AstraZeneca, manufacturers of the Oxford vaccine - promised not to seek government approval of any vaccine without extensive safety and effectiveness data.

"We believe this pledge will help ensure public confidence in the scientific and regulatory process," they said.

The Oxford, AstraZeneca trial has now been delayed while a safety issue is investigated.

Elsewhere, Chinese firm SinoVac reported that its vaccine appears to be safe in older people in mid-stage trials, although it generated a slightly weaker immune response compared with younger adults.