Pfizer vaccine: How will doses be stored and transported at low temperatures?

The UK has become the first country in the world to approve the Covid-19 vaccine developed by Pfizer and BioNTech, with an estimated 800,000 doses set to be made available next week.

But amid hopes of a rapid rollout, authorities are faced with the logistical challenge of storing the vaccine at around -70C.

So, what happens next?

Pfizer has said it intends to manufacture up to 50 million doses globally in 2020. These will be manufactured and distributed from the company’s various production sites in the US, Germany and Belgium.

The pharmaceutical giant said it expects 20 planes will be taking flight daily around the world to deliver the doses to the relevant countries, where the doses will then be transported to distribution centres. Pfizer has already ruled out ocean transport due to time constraints.

Once the vaccine supply arrives in the UK, it will undergo quality checks to ensure it has been shipped safely.

How will the vaccine be kept cold?

Supplies of the vaccine can either be stored in ‘freezer farms’ at -70C, which will maintain the integrity of the doses for up to six months.

But if the shots are on the go, this makes matters far more complicated. There has never been been a drug that requires storage at such low temperatures, meaning the necessary ‘cold-chain’ is being rapidly put together on a rolling basis.

To get around the problem of storage, Pfizer has developed a specially built deep-freeze "suitcase" that can be tightly sealed and transported even in non-refrigerated trucks.

These boxes are with packed with dry ice (solid carbon dioxide) and installed with GPS trackers, which will allow Pfizer to remotely track the location and temperature of the frozen vaccine vials. Each reusable box can keep up to 5,000 doses of the vaccine at the right temperature for 10 days.

The thermal shipping systems can be recharged with dry ice if needed, Pfizer said.

The boxes can only be opened twice a day for less than three minutes at a time while maintaining temperature standards.

Distributing and administering doses

The deep-freeze suitcases will give authorities 10 days to transport doses from the UK’s distribution centres to dedicated vaccination centres across the country.

A number of venues have already been earmarked, including sports halls, leisure centres and even the Copper Box stadium in London's Olympic Park. The NHS Nightingale Hospitals are also being considered.

Once delivered, the vaccine can be stored in traditional fridges (2C-8C) for up to five days, meaning authorities will have to move quickly in administering all available doses among priority groups.

Because of the logistics involved, local GPs are unlikely to have access to supplies any time soon, though Public Health England has said that longer-term “national preparations” are under way regarding central storage and distribution across the country.

It is expected that at first the rollout will begin in hospital sites with sub-zero freezing capacity, to stop the vaccine vials from thawing too quickly. Health secretary Matt Hancock said on Wednesday morning that 50 hospitals in UK are already set up and waiting to receive supplies.

Pfizer's vaccination requires two doses 21 days apart, making it more complicated to deliver the required number of shots and ensure supplies do not go to waste.

Health secretary Matt Hancock said: "This is a challenging rollout and the NHS in all parts of the UK stands ready to make that happen.

"They are used to handling vaccines and medicines like this, with these sorts of conditions.

"It's not easy but we've got those plans in place, so this morning I spoke to my counterparts in the devolved nations to make sure that we are all ready to roll out this vaccine ... from early next week."

Professor Arne Akbar, president of the British Society for Immunology, said: “This announcement is not the end of the story and there is still much work to do. Roll out of the vaccine is going to be a logistical challenge and rely on our dedicated healthcare professionals around the country.”