When plans for the rule were first revealed by The Telegraph last May, about 155,000 NHS workers had yet to have their first jab.
NHS guidance to employers says all frontline staff who have not been vaccinated should start being called into formal meetings from February 4 and warned that they face dismissal.
This process is currently continuing, with no instructions issued to the NHS about any delay to the timetable.
But on Wednesday Sajid Javid, the Health Secretary, told MPs that the policy was now “under review”, given the “the very different” and “less severe” nature of the omicron variant.
Mr Javid said while some people had urged him to add boosters to the mandatory requirement, others have called for it to be scrapped altogether.
He said: “I think it is right in light of omicron that we reflect on all this and keep all Covid policies properly sort of under review, because omicron is different to delta.
“Equally, we don’t know what the next variant is going to be … But we are reflecting on all this.”
Ministers are expected to consider Thursday’s data, the last due to be published before the February 4 deadline, as they prepare to take a decision on the timetable ahead.
First jabs are required by the deadline in order to allow time for a second dose by the start of April, when the rules apply.
Compulsory jabs were introduced for care workers, but uptake was significantly lower – at 91.1 per cent – eight weeks before vaccines became mandatory last November.