More than 12 million people in Britain have been vaccinated against Covid-19, according to government figures released on Sunday.
The government is aiming to offer a vaccine to all 15 million of the country's most vulnerable people by mid-February, including those over 70, health care workers and those with pre-existing conditions.
The government is confident it will reach this target, and aims to offer everyone above the age of 50 a jab by May.
Thanks to early, rapid procurement, Britain is suffering less from vaccine manufacturing bottlenecks than some countries in the European Union.
The WHO has already called on Britain to share surplus doses of the vaccine after vulnerable groups have been vaccinated. If all of the vaccines Britain has ordered are approved and supplied, the country would have three times more vaccines than are needed.
However, the head of the British Vaccination Taskforce, Kate Bingham, said Brexit was not responsible for the success of the country's vaccine roll-out, in an interview with Welt am Sonntag newspaper.
Instead, she attributed this to experience in the industry, good contacts and willingness to sign contracts early on.
Meanwhile, cases of new variants of the virus have dropped in recent weeks, thanks to the lockdown in place in Britain.
At times, there were more than 70,000 cases per day in December.
Britain recorded 218 new cases of the virus per 100,000 people during the past seven days.