Speaking to Parliament on Wednesday, Prime Minister Boris Johnson told lawmakers the only thing slowing down the vaccination programme was access to vaccines.

Responding to a question from the opposition leader, Keir Starmer, concerning reports of overnight-operating vaccine centres, Johnson replied: “I can tell him that we’ll be going to 24/7 as soon as we can, and the Health Secretary will be setting out more about that in due course.”

“At the moment, the limit is on supply. We have a huge network of 233 hospitals, 1,000 GP surgeries, 200 pharmacies and 50 mass vaccination centres. They are going exceptionally fast [in implementing the programme] and I pay tribute to their work.”

Almost 2.5 million Britons have had their first vaccine dose, which is considerably more than anywhere in the EU.

Speaking earlier on Wednesday, virologist Dr Chris Smith, interviewed on the radio programme Jeremy Vine On 5, said a nighttime coronavirus jab might not be as effective.

Smith argued that a dose administered at night might trigger a “more limited” immune response.

The prime minister also insisted that the new national lockdown, which took effect from January 5, was starting to have an impact on infection rates.

“It’s early days. People must keep their discipline, keep enforcing the rules, and work together to roll out that vaccine programme,” he added.

The UK has registered more than 40,000 new infections every day since late December.