Nurses at the Royal Free Hospital, London, simulate the administration of the Pfizer vaccine to support staff. [AP]

Britain is preparing to become the first country to roll out the Pfizer/BioNTech Covid-19 vaccine this week.

It will initially make the shot available at hospitals before distributing stocks to doctors' clinics, the government said yesterday. The first doses are set to be administered tomorrow, with the National Health Service (NHS) giving top priority to vaccinating the over-80s, frontline healthcare workers and care home staff and residents.

Britain gave emergency use approval for the vaccine developed by Pfizer and BioNTech last week - jumping ahead in the global race to begin the most crucial mass inoculation programme in history. Britain has ordered 40 million doses. As each person requires two doses, that is enough to vaccinate 20 million people in a country of 67 million.

About 800,000 doses are expected to be available within the first week.

Initial doses that have arrived from Belgium are being stored in secure locations across the country, where they will be quality checked, the health ministry said.

The Pfizer/BioNTech vaccine has onerous storage requirements. It needs to be kept at -70C (-94F) and only lasts five days in a regular fridge.

For that reason, the health ministry said the vaccine would first be administered in 50 hospitals. It said it would take a few hours to defrost each vaccine and prepare it for use.

NHS England has written to general practitioners, telling them to get ready to start giving vaccinations through local doctors' services from December 14.

Rather than run clinics in individual surgeries, groups of local doctors will operate more than 1,000 vaccination centres across the country, the government said.