Doubts have been cast over whether the final stage of the Government’s road map out of lockdown can proceed on June 21.

Some scientists have said that the final easing of social restrictions in England should be delayed, others have said that the cost to society will be too great if it is.

But what will the Government consider while making its decision for the so-called “great unlocking”?

Here are the four tests that ministers will consider as they make their decisions.

1. Is the vaccine deployment programme continuing successfully?

Undoubtedly. The UK has been hailed as having one of the most successful vaccination programmes in the world. Targets to vaccinate certain groups have been met with ease, and often ahead of time.

In England and Scotland, all over-30s are being asked to come forward for their vaccine. In Northern Ireland, people over the age of 25 can get their jab. In Wales, all adults can book in for their jab.

Almost three-quarters of all British adults (74.8%) have had their first jab and almost half have had their second (48.5%).

And vaccines minister Nadhim Zahawi said that ministers hope to have all over-50s and clinically vulnerable people fully vaccinated with both doses before June 21.

2. Does the evidence show vaccines are sufficiently effective in reducing hospital admissions and deaths in those vaccinated?

So far the evidence is very positive. Even against the new variant of concern which was first identified in India.

When experts use the term “vaccinated”, they mean the people who have had the full protection from both doses of vaccine – not those who have only had one jab and are awaiting their second.

NHS leaders have said among people admitted to hospital only a handful have had two doses.

Public Health England has estimated that the vaccine programme has prevented 13,200 deaths in England alone among adults aged 60 and over.

And among those aged 65 and over, 39,700 hospital admissions have been prevented, according to PHE estimates.

3. Do infection rates risk a surge in hospital admissions which would put unsustainable pressure on the NHS?

Probably not. Hospital admissions have been rising in some hotspot areas. But NHS leaders have said that hospital admissions now look very different to the admissions which were seen in January and February.

The majority of people who are being admitted to hospital are younger and easier to treat.

Patients are generally being looked after on acute and general wards, instead of in critical care. Some will spend three to four days in hospital and be treated with oxygen and dexamethasone before being discharged.

It must be said that over the last seven days there have been 870 hospital admissions across the UK.

4. Is the Government’s assessment of the risks fundamentally changed by new Variants of Concern?

The final test is a bit more tricky. Cases of the variant first identified in India almost doubled in a week and scientists have warned that the variant appears to be more transmissible than the variant first identified in Kent.

Data from PHE suggests that the Pfizer and AstraZeneca jabs offer high levels of protection against symptomatic disease from the variant first identified in India among those who have had two doses of the jab, which in turn is likely to lead to even higher levels of effectiveness against hospital admissions and deaths.

As with any virus, variants can emerge all the time. And one only has to look at other countries whose health systems have faced near collapse under the strain of new variants.

Will the vaccines be as effective against future variants? Without a crystal ball, we would be unable to tell. But the evidence so far is extremely positive.

– Does this mean that the great unlocking will go ahead on June 21?

The Government’s road map out of lockdown states: “Only when the Government is sure that it is safe to move from one step to the next will the final decision be made.”

Ministers have two weeks to deliberate the decision. And the Government’s former chief scientific adviser said ministers need more data before ministers can make a final decision so unfortunately the nation will remain in limbo for another fortnight while the data rolls in.

Those advising the Government will pay particular mind to data concerning the new variant first identified in India, information on hospital admissions, and what has happened since the relaxation of other measures on May 17.