Rolling out a Covid vaccine to the masses could pose a “mammoth logistical operation”, the Health Secretary has said.

Matt Hancock highlighted some of the key obstacles in getting the Pfizer/BioNTech vaccine rolled out – should it be approved by regulators.

The vaccine, which provided early promising results from clinical trials on Monday, needs to be stored at minus 70C – which could pose transport and storage issues.

But Mr Hancock said that from the moment the vaccine leaves the factory in Belgium it can only be taken out of minus 70C four times before it is injected into a patient’s arm.

But it can be stored at a warmer temperature in the two days prior to being used, Mr Hancock said.

This implies that GPs will be able to administer the vaccines two days after deliveries without the need for new refrigeration systems.

But transportation of the vaccine from the factory in Belgium to GP practices across Britain could pose a problem.

But one expert said the hurdles could be overcome.

Dr Simon Clarke, associate professor of cellular microbiology at the University of Reading, said on Monday: “There are production and distribution problems to be overcome, but these should not be beyond the wit of human ingenuity.”

Quizzed on the positive results from Pfizer and BioNtech, Mr Hancock told BBC Radio 4’s Today Programme: “We haven’t got a vaccine yet, we’re not there yet, but we are one important step closer, and we’ll be ready to deploy it.”

He added: “There’s an enormous challenge of the rollout – we bought doses for 20 million people – 40 million doses in total; it takes two doses 21 days apart (and) it has to be stored until the last few hours before deployment at minus 70C.

“This is going to be a colossal effort to roll this out which the NHS is leading – we’ve been working on it for months in anticipation of this going right.”

Mr Hancock added: “It has to be kept at minus 70C and, crucially, the other trickiness is that it can’t be taken out of minus 70C more than four times – from the moment it leaves the factory gate to the moment that it is injected into somebody.

“For the last 48 hours it is okay to have it at a higher temperature – for it to still be cold in a way that GP surgeries can deliver.

“And in fact, GPS are going to play a huge role in this.”

He said the NHS will be working seven days a week to roll out the vaccine, adding: “A combination of hospitals and core parts of the NHS, having big vaccination sites where people can go to, plus GPs… pharmacists have an important role to play.”

Meanwhile, teams will be sent to deliver the vaccine to some people, such as those in care homes.

“It is a mammoth logistical operation which the NHS is leading,” the minister said.

The necessity for this temperature of storage also poses problems surrounding the distribution of the vaccine globally.

Some low income countries face significant challenges when transporting vaccines which only need to be stored in refrigerators at 4C – let alone minus 70C.

Dr Charlie Weller, head of vaccines programme at Wellcome, told the PA news agency: “The cold chain that’s needed, that’s going to be a challenge where there are health systems and countries where that cold chain is not set up, or it is not able to be set up in a timely manner.

“So that is going to potentially mean that we need different options, we need a range of vaccines.”