Britain's healthcare providers are gearing up to start giving the first doses of the Pfizer/BioNTech vaccine, less than a week after the United Kingdom became the first Western nation to approve a Covid-19 vaccine.

Vaccinations are set to begin on Tuesday in England, Wales and Scotland. Northern Ireland said it would start administering the vaccine early in the week but did not specify which day.

The process, which is complicated by the need to store the Pfizer/BioNTech vaccine under strict conditions and give each recipient two doses, three weeks apart, will be closely watched from around the world.

Saffron Cordery, deputy chief executive of NHS Providers, told Sky News on Sunday that 50 hospital hubs across England had already received their allocation of the vaccine, and that the distribution of the vaccine was "really well underway now."

UK health officials expect to have up to 4 million doses of the Pfizer/BioNTech vaccine, which offers up to 95% protection against Covid-19, available by the end of December, Cordery said.

The government has ordered 40 million doses of the Pfizer/BioNTech vaccine so far, enough to vaccinate 20 million people, or a third of the UK population. More deaths from Covid-19 have been recorded in the UK than anywhere else in Europe.

The speed with which UK regulators approved the vaccine -- ahead of their counterparts elsewhere in Europe and in the United States -- raised questions in some quarters. But Cordery said the process had been "incredibly robust."

"Yes, it has been shorter than other vaccine approval processes, but that's because everything all has been thrown at this all in one go," she said.

The head of the UK medicines regulator also put out assurances on Sunday, saying the Pfizer/BioNTech jab is "as safe as any general vaccine" and that those receiving it would be monitored by health officials.