Britons in their forties who tried to book a booster jab for the first time today joked it was a case of 'computer says no' as the NHS site was plagued with technical difficulties.
The booster campaign was officially opened to the age group today after ministers slashed the wait time between the second and third jabs from six months to three to shield against the incoming Omicron wave.
Some who tried to book were told they were ineligible despite having their second Covid vaccine more than three months ago, while others said the 119 phone system hadn't been updated to embrace the rule change.
Professor of law and society Chris Ashford was one of those who knocked back by the booking system, despite being urged to come forward for his jab. He described the situation as '#computersaysno'.
In another case, journalist Helen Pidd said the NHS booking system told her husband he was ineligible for the jab despite getting his second in July.
News of booking system troubles come a day after official Government data showed the booster campaign had failed to accelerate, despite promises from No10 to put the drive on 'steroids'.
Britain has pinned its hopes of fending off the mutant Omicron variant on the rollout and Boris Johnson has promised to offer all 53million eligible adults in Britain a jab by the end of January — even though it could take until February at the current rate.
Some over 40s have said the NHS booking system for the Covid boosters is telling them they are not currently able to get a jab
Professor of law and society Chris Ashford said it was a case of 'computer says no' when it came to attempting to book his Covid booster
In a message to health secretary Sajid Javid Helen Pidd said her husband was unable to book a Covid booster, despite having got his second jab five months ago
Pamela Nally was another person who should have been able to book a jab, but the NHS booking system told her she wasn't eligible
Professor Ashford, who was one of those affected was one of those who knocked back by the booking system, joked the situation was a case of s '#computersaysno'.
'I’ve read multiple news stories this morning that I am now in the group eligible for a booster vaccine and can book. Nobody seems to have told the NHS booking system,' he wrote.
In a follow up message he added the situation was: 'A mind bogglingly poor use of resource and messaging.'
Ms Pidd, an editor for The Guardian, told health secretary Sajid Javid that her husband was unable to book his jab today, despite getting his second Covid vaccine five months ago.
'Sajid, the website hasn't yet been updated. 40-somethings can still only book for the booster if their second dose was 152 days+ ago. Just rang NHS to check and they said to wait until the booking service is updated. My husband gets this message and had his 2nd dose in July,' she wrote.
Data manager, Pamela Nally, said the NHS website was failing to recognise her previous jab: 'Should be able to book my #COVIDBooster but site not recognizing my vaccination and #119 not updated to allow booking past 5 month'.
In announcing today's launch of the booster booking system for the over 40s, the NHS hinted that there might be issues.
A statement from NHS England outlined that the system would be updated over the course of the day: 'The online booking system for vaccines will be updated this morning and details will be updated on the system throughout the day,' it reads.
The NHS estimates that 7million people should have become eligible to book their Covid booster today.
It's not the first time the NHS Covid vaccine booking system has run into trouble, in April the website crashed due to demand after the vaccines were opened up to the over-45s.
And yesterday, Boris Johnson today insisted that Britain's Covid booster campaign was actually going faster than planned, despite data showing the country is still nowhere near meeting his 500,000-a-day target.
The Prime Minister last week promised to put the rollout on 'steroids' and ramp up the number of third doses delivered.
The current rate of the booster rollout means Britain will miss the deadline to offer every eligible adult a Covid booster shot by the end January, instead hitting this target by 10 February
When questioned about the speed of the booster programme yesterday, Mr Johnson claimed it was actually ahead of schedule, before adding it could go faster .
He told reporters: 'The booster programme is the fastest in Europe, and I think we've done more boosters than any comparable country. That doesn't mean it couldn't go faster.
'We're ahead of our own timetable, we've done more than 20million boosters, I think we've done three-quarters of the people aged over 65.'
Mr Johnson added that he expected a booster acceleration once the programme is finally opened to under-40s next week.
'And of course, from Monday, we will be contracting the intervals so you go down to three months and that will lead to a big uptick in the programme as well,' he said.
Latest NHS data shows the UK is nowhere near the 500,000-a-day goal and is in fact delivering fewer booster jabs on some days than before Mr Johnson's pledge.
Data published today lad bare the sluggishness of the booster programme with only 329,165 jabs given on Monday, the date for which the latest figures are available.
Despite promises to ramp up the scale of the booster rollout the is only about 10,000 more jabs than the same day last week, when 318,671 were given.
At the current speed of 2.7million per week, it will take until mid-February for every eligible Briton to be offered get their third Covid vaccine, almost two weeks after the Government's end of January deadline.
The tech issues have slightly marred the rollout of the booster programme to the over 40s, coming on the one-year anniversary of the NHS delivering the first of the Covid vaccine in the UK.
One-year-ago today, British grandmother Margaret Keenan became the first person to become vaccinated in the UK and the world to receive a Covid vaccine outside of a medial trial, and launched the largest vaccine programme in history.
Several NHS and Government officials today urged people to get their booster shot as soon as possible to protect the country against Omicron.
NHS England chief executive Amanda Pritchard urged people to come forward and book their booster as soon as possible to protect themselves from Omicron.
'There is a lot we do not know about the Omicron variant but experts believe that even if existing vaccines are less effective they will give protection,' she said.
'So I would urge anyone eligible to come forward as soon as possible, and to keep checking for appointments in their area.'
Mr Javid also got in on