People over the age of 50 that have not yet had their jab are being urged to book their appointment as soon as possible.
Professor Stephen Powis, the NHS' National Medical Director, has called on anyone who is eligible but has not yet received the first jab to book an appointment in the next few days.
The NHS is expecting a slowdown in the UK vaccine supply for the whole of April, meaning medics will concentrate on delivering second doses, with fewer first appointments available.
Earlier this month an NHS letter warned the UK faces a "significant reduction" in coronavirus vaccine supplies from 29 March, for an estimated four-week period.
The letter - which has been sent to local vaccination sites across the country - says volumes for first doses are going to be "significantly constrained".
NHS England has said no first appointments should be booked for people under the age of 50 unless they fall into a higher priority group, such as those who are clinically vulnerable.
Prof Powis said: "It is a testament to the careful planning and sheer hard work of staff that the NHS vaccination programme is continuing to protect people against coronavirus at a record pace.
"I was thrilled to get my first dose earlier this month, it was quick, painless and safe and it feels great knowing I've got protection against COVID-19 - so if you are eligible, do not delay, book a jab."
Health Secretary Matt Hancock previously said that the upcoming vaccine supply would be "lumpy" heading into April thanks to a reduction in doses available.
He told MPs the drop was caused by a need to re-test the stability of 1.7 million AstraZeneca vaccine doses as well as a delay in jabs from the Serum Institute of India (SII).
© Sky News 2021