James Paton And Naomi Kresge Bloomberg

Now that Britain has become the first western country to approve a Covid-19 shot, the spotlight shifts to the high-stakes rollout. Vaccinating the country's roughly 67 million people won't happen overnight. The UK has ordered enough doses of the two-shot Pfizer-BioNTech vaccine to immunize 20 million people.

The U.K. became the first western country to approve a Covid-19 vaccine, with its regulator clearing Pfizer Inc. and BioNTech SE's shot ahead of decisions in the U.S. and European Union.

Now that Britain has become the first western country to approve a Covid-19 shot, the spotlight shifts to the high-stakes rollout. Vaccinating the country's roughly 67 million people won't happen overnight. The UK has ordered enough doses of the two-shot Pfizer-BioNTech vaccine to immunize 20 million people.

The U.K. became the first western country to approve a Covid-19 vaccine, with its regulator clearing Pfizer Inc. and BioNTech SE's shot ahead of decisions in the U.S. and European Union.