The average number of COVID-19 vaccinations delivered per day UK-wide in the first seven days of April is 319,732 - a sharp drop from the daily average of 469,988 for March.
Figures published by the government also show the marked shift in focus of the UK vaccination campaign towards second-dose vaccinations amid an expected dip in supply this month.
In March, one in four doses of COVID-19 vaccine administered UK-wide were second doses - while in the first seven days of April, 71% of all doses administered have been second doses.
A total of 225,492 second-dose vaccinations were delivered UK-wide per day on average in the first seven days of April, analysis by GPonline shows, compared with the 94,240 daily average for first-dose vaccinations in the same period.
The NHS was forced to warn vaccination sites last month that supplies of vaccine would not meet the high levels previously expected through April - slowing the rollout of first-dose jabs to adults in younger age groups.
Health and social care secretary Matt Hancock said last month that despite the dip in supply, some first-dose vaccinations would continue in every week of April. So far, some first doses have been administered every day this month - although between 4 and 7 April first-dose jabs dropped below six figures per day for the first time since data on the vaccination campaign were first published in early January.
COVID-19 vaccine second dose
The two highest totals for second-dose vaccinations within a single day UK-wide have come in April, with 408,396 second doses delivered on 7 April, and 445,416 second doses on 1 April.
More than 12m people UK-wide are due a second dose of vaccine this month after receiving their first dose earlier in the year.
In a letter to Mr Hancock this week, the Joint Committee on Vaccination and Immunisation (JCVI) backed the use of the third vaccine approved for use in the UK - the Moderna vaccine - in both the first phase of the vaccination campaign covering cohorts 1-9, and the next phase which will deliver vaccinations to all adults.
The JCVI letter said: 'The committee advises delivery of the first dose of the Moderna to as many eligible individuals as possible should be initially prioritised over delivery of a second vaccine dose, in line with our published advice.
'The second dose of the Moderna vaccine may be given in the committee’s view between 4 to 12 weeks following the first dose. This will be "off-label" use of the vaccine, which the committee agree is necessary in the current pandemic situation. As with the other COVID-19 vaccines authorised for use in the UK, JCVI advises that the first and second doses should be with the same vaccine whenever possible.'
The first UK dose of the Moderna vaccine was administered this week in Wales.