When the Government set out its roadmap in February, Boris Johnson said the release dates would go ahead so long as four tests were met.
The vaccine programme needed to continue apace; vaccines must prove effective in reducing hospitalisations and deaths; infection rates should stay low; and variants should not change the overall risk.
So have those tests been met, and is there really a need for a further, four-week delay?
Test 1: The successful vaccine programme continues
Clearly the vaccine rollout has been a tremendous success, with 78.9 per cent of the adult population having had at least one dose, and 56.6 per cent now fully vaccinated.
The programme, which is jabbing between 500,000 and 750,000 people a day, has taken millions of vulnerable adults out of harm’s way, and dramatically cut the risk of catching the virus, being admitted to hospital, or dying.
Public Health England’s (PHE) latest vaccine surveillance report shows that more than 98 per cent over-50s in England now have antibodies to coronavirus, either through vaccination or a previous infection, and very few people in older groups are now ending up in hospital.
Overall, more than 77 per cent of the adult population now has protection to Covid-19 from either infection or vaccination and crucially, the under-30s are now being vaccinated which could have a big impact on the current spread of the virus.
Figures show that the virus is now predominantly circulating in younger and unvaccinated people, with the case rate for 20 to 29-year-olds at 121.0 per 100,000 population, compared to just 6.7 per 100,000 for the over-80s.
So getting a handle on infections in younger adults will hopefully nip the new wave in the bud.
Any pause in lifting restrictions will also allow more people to have their second dose. Edward Argar, the health minister, said 10 million people would be given their second vaccination during the four-week delay.
Dr Simon Kolstoe, senior lecturer in evidence based healthcare, University of Portsmouth, said: “Mass vaccination is clearly working. But we can only be confident in lifting all restrictions once we know that the link between large scale infections and hospital admissions has been broken.
“The vaccine certainly seems to be doing its job in breaking this link, but a few more weeks to get more people vaccinated certainly seems like a sensible option.”
Test 2: Vaccines are effective in reducing the number of people in hospital
It is now an undisputed fact that vaccines have played a major role in lowering admissions and deaths. Latest estimates from PHE suggest that around 42,000 hospitalisations have been prevented by the roll-out and 14,000 deaths.
Data released on Monday from the University of Edinburgh and Public Health Scotland (PHS) shows this is holding true even for the delta or Indian variant. Although it is now believed the mutated virus doubles the risk of being admitted to hospital, the risk is cut by 70 per cent for people who have been fully vaccinated.
Although the team found there was a slight dip in vaccine effectiveness between the alpha, or Kent, and delta variants, they also found there are "very few" over-65s testing positive for Covid-19, suggesting the jabs are protecting the most vulnerable.
Modelling warns variant could overwhelm hospitals
The Scottish team calculated that for people who had two doses, or who had their first dose at least four weeks ago, the risk of being hospitalized with the Alpha variant was reduced by 72 per cent and the Delta variant by 62 per cent.
Data released from Public Health England (PHE) suggests the Pfizer-BioNTech vaccine is 96 per cent effective against hospitalisation after two doses, while the Oxford-AstraZeneca vaccine is 92 per cent effective against hospitalisation after two doses.
Many of the original outbreaks of the Delta variant were in low areas of vaccination, and in areas where there has been a huge effort to encourage uptake, such as Bolton and Bedford, case numbers have dropped.
Dr Jim McMenamin, National Covid-19 incident director, at PHS: “The vaccines are offering not just the prospect of a way for communities to move back to normality but actual evidence that is happening from the results we have.”
Latest figures from PHE also show that just five per cent of delta variant infections are in people who have been fully vaccinated.
The new data also show that the death rate is still very low, with just 0.1 per cent of people – one in 1,000 – infected by the variant going on to die. In comparison, the death rate for people catching the Alpha variant is 1.7 per cent – 17 in 1,000.
So far, there have been just 42 deaths from the delta variant, and only 12 in fully vaccinated people.
Test 3: Surging infection rates and more people in hospital
This is clearly a sticking point for the Government as infection rates have been surging in recent weeks.
Latest testing data shows a 50 per cent rise from last week, and admissions and deaths have also started to creep up, after big reductions in the spring.
One of the issues is that the NHS is now facing a huge backlog from health services that were paused during lockdown, or where people did not seek medical help.
There are fears among NHS leaders that even a slight rise in Covid-19 cases could push hospitals to breaking point, although Trusts in hotspots such as Bolton have said they have coped well with the current wave.
There is also good evidence that people who are being admitted to hospital are less sick, require shorter stays, with most unlikely to need intensive care.
NHS wait times
The most recent Intensive Care & National Audit Research Centre (Icnarc) report shows that just 169 patients have been admitted to intensive care with Covid-19 in the past month in England, Wales and Northern Ireland, equating to fewer than six cases per day.
Statistics show that out of 3,394 patients admitted to hospital in May, only around five per cent needed intensive care. At the peak, 72 per cent of intensive care admissions were due to Covid-19 compared with less than 20 per cent at the moment.
The Icnarc data also shows that the chance of dying within 28 days of admission to intensive care has now fallen to 20 per cent, compared with around 45 per cent during the first wave.
Test 4: New variant has not changed scientific assessment of the risk
Undoubtedly, the risk of unlocking has changed based on analysis of the most recent variant.
Latest estimates suggest that the delta variant is between 41 and 60 per cent more transmissible than alpha, and the risk of being hospitalised is about double.
Mark Woolhouse, professor of infectious disease epidemiology, University of Edinburgh, said: “The arrival of the delta variant has changed the assessment of the risks of re-opening: it is more transmissible, causes more severe disease, and the vaccines are less effective against it.
Where is the Indian (Delta) variant in the UK?
“The current situation can be said to fail the fourth of the four tests the UK Government set out in February.”
However, not only do vaccinations still appear to be working, but the variant itself may be becoming less infectious. The number of contacts being infected by a carrier has also dropped, from 13.5 per cent to 11.3 per cent in the last two weeks.
Essentially, Britain is now experiencing an epidemic of the unvaccinated.
PHE figures show that two thirds of the 1,234 people with the delta variant who attended A&E in England between Feb 1 and June 7 were unvaccinated.
Of the 383 cases where attendance at A&E resulted in an overnight admission, 251 (66 per cent) were unvaccinated, and just 42 (11 per cent) were more than 14 days after a second jab.
It is also worth noting that hospital occupancy was forecast to be much worse by now under scientific modelling used to inform the roadmap.
Although there are concerns about hospital numbers, with Covid-19 in-patients currently around 1,090, the figures are still far less than the Government feared might happen when it announced its release dates in February.
Even under a cautious scenario three, in which Freedom Day was moved to July 5, hospital occupancy was forecast by the University of Warwick to be around 1,750 by now, while Imperial College suggested it would be closer to 7,000.
So Britain is actually doing far better than was expected when the roadmap was released.
Undoubtedly, the risk of unlocking has changed based on analysis of the new variant, and the Government has now accepted it has failed Test 4, which also places it in danger of failing Test 3.