The NHS COVID-19 Vaccination Programme has vaccinated almost half of those eligible with a spring booster a month after the campaign's formal launch.
More than three million people have taken up the offer of a spring COVID jab to keep up their protection from the virus.
Around 6.6 million people are eligible, including those aged 75 and over, with a weakened immune system or care home residents.
The offer formally opened to everyone outside of a care home on 17 April.
NHS staff have also been going into older adult care homes to offer residents the vaccine since 3 April.
NHS Director of Vaccinations and Screening Steve Russell said: “One month into the NHS COVID-19 Vaccination Programme's spring campaign, more than three million people have come forward for a booster to keep up their protection from COVID - that's almost half of everyone eligible.
“While the NHS has been able to stand down the COVID incident - thanks in large part to the success of the vaccination programme - the virus is still with us and we must continue to ensure the most vulnerable in our society continue to receive this important protection.
“If you are one of those due a jab this spring but yet to come forward - please do book an appointment online or via the NHS App as soon as feasible”.
The campaign is set to end on 30 June when the offer of a first or second dose for anyone yet to come forward will also end as COVID vaccinations move to a seasonal targeted offer.
Health and Social Care Secretary Steve Barclay said: “The COVID-19 Vaccination Programme continues to give people the protection they need and nearly half of those at greatest risk of the virus have already had their spring booster.
“I'd like to thank our fantastic roving NHS teams, who've been visiting care homes to make sure those at risk get their jab to protect them from COVID.
“Getting your vaccine couldn't be easier with thousands of sites open across the country, and I would urge anyone eligible to come forward as soon as possible”.