The total number of vaccinations per day administered across the UK peaked at 324,233 on Friday 15 January - but has since fallen well below 300,000 per day to a low of 204,076 on 18 January.
Government figures show that by the end of 18 January, a total of 4,266,577 people had received a first dose of COVID-19 vaccination - leaving just over 10.7m to go to hit the 15 February target.
However, with 28 days to go from 18 January, the number of COVID-19 vaccinations per day needs to average 383,337 - 18% more than the maximum daily figure achieved to date.
Health and social care secretary Matt Hancock said this week that the government was 'shovelling out' supplies of COVID-19 vaccine as fast as possible.
COVID-19 vaccine supply
He admitted there were 'movements in supply' - and reiterated the government line that supply was the 'rate limiting factor' holding back the vaccination campaign.
Responding to questions at a Downing Street briefing he said: 'Making sure we get the supply into people's arms as soon as possible is critical. I wouldn't read too much into an individual day's data - I think the best thing to do is look at the weekly averages - you can see that going up and going up fast.'
GPonline has reported on GP-led vaccination sites warning they are unable to vaccinate at maximum capacity because supply of vaccine has not kept up with demand.
Mr Hancock said this week: 'We are prioritising supply of the vaccine into those parts of the country that need to complete the over-80s.But we don't want to stop the areas that have done that already, we want them to carry on, but the priority is the Joint Committee on Vaccination and Immunisation (JCVI) priority list.'
He said variations in the speed of rollout in different parts of the country were driven by 'all sorts of reasons' - but said everyone in the top four priority groups set out by the JCVI 'will be offered a vaccine' by 15 February as planned.