Half of all adults aged under 30 in England will have received a first dose of a Covid-19 vaccine by Sunday, the NHS has said.

More than 4.2 million people aged between 18 and 29 have received a jab just three weeks after the coronavirus vaccination programme was opened up to those in their 20s.

The achievement comes as hundreds of walk-in vaccination sites, including at stadiums and shopping centres, opened in England this weekend in a bid to boost vaccine numbers amid rising coronavirus cases.

A new online search tool allows people in England to input their postcode to find their nearest walk-in vaccination site.

The “grab a jab” campaign comes as the UK recorded a further 15,810 lab-confirmed Covid-19 cases as of 9am on Friday – up 50% on the 10,476 new cases reported a week earlier.

Meanwhile, the Department of Health and Social Care (DHSC) said that the UK had now genomically sequenced more than half a million positive Covid-19 samples.

This genetic make-up data is used to identify new variants and help suppress the spread of the virus, with it estimated that the UK contributes about half of all sequencing shared for comparison around the world.

The DHSC said that such work, which is informed by the rollout of surge testing, will help support decisions over relaxing social distancing rules in the future.

Dr Jenny Harries, chief executive of the UK Health Security Agency, said: “Sequencing genomes has been one of most versatile tools in our armoury in the battle against Covid-19, and as we progress down the road map its role only increases in importance – helping us track mutations in the virus and act decisively to stop cases becoming outbreaks.”

According to NHS England data released on Saturday, a total of 64,089,251 vaccinations took place in England between December 8 and June 25, including first and second doses.

NHS England said 36,944,843 were first doses, a rise of 177,515 on the previous day, while 27,144,408 were a second dose, an increase of 133,375.

More than four in five adults have now received their first jab and over 60% of people have received both doses, the NHS said.

More than one million vaccination bookings were made between Monday and Wednesday this week, while the NHS is also contacting people aged 40 and over to bring forward their second dose in line with updated expert advice.

Dr Nikki Kanani, NHS England director of primary care, hailed the “incredible” progress being made.

She said: “The uptake we have seen among 18 to 29-year-olds in the last week shows how much young adults – like all those before them – recognise the importance of getting protected, as the NHS continues to deliver the largest and fastest vaccination programme in history at a phenomenal rate.”

Dr Kanani added: “NHS teams and their local partners are working flat-out this weekend to vaccinate as many people as possible at convenient walk-in sites up and down the country so if you are 18 and over, go along and ‘grab a jab’ – with every vaccine in an arm, we are one step closer to our summer freedoms.”

Vaccines minister Nadhim Zahawi said: “This is a phenomenal achievement and it’s fantastic to see so many young people coming forward for their jabs, doing their bit to protect themselves and their loved ones.

“I’d like to recognise the herculean efforts of all those who are working tirelessly to vaccinate as many people as quickly as possible and would like to pay my thanks to all the NHS staff, volunteers, local authorities and civil servants for their commitment.

“Vaccines are the way out of this pandemic and I’d urge everyone – regardless of age, religion or beliefs – to get their jabs so we can beat this virus and reclaim all of our lost freedoms.”