The Health Secretary, Matt Hancock, and other government ministers have insisted the UK is on track to hit a target of offering a Covid-19 vaccine to almost 14 million people by the middle of next month.

But questions remain about the supply of vaccines. Will the government hit this target, and others that have been mentioned by ministers?

What is the target exactly?

On January 4, Boris Johnson first set out the target of offering the first dose of a vaccine to the top four priority groups identified by the government’s main advisory body on vaccinations by February 15.

The number was initially put at 15 million people, but Matt Hancock said in a BBC Radio 4 interview today that the first four categories amounted to 13.9 million across the UK.

The target has always been to “offer” people the first dose. Since vaccines are not mandatory in the UK, it’s expected that some people will decline the offer, so the government cannot guarantee the number of vaccinations that will actually be done.

Sir Simon Stevens, chief executive of NHS England, told MPs on Monday that the government was expecting around three-quarters of people offered a vaccine shot to take up the offer, but said there was “enough vaccine, provided that supply carries on coming onstream as we expect it to” to cover ensure coverage even if everyone takes up the offer.

In case there was any suspicion about the meaning of the February 15 deadline, Matt Hancock told the Health and Social Care Select Committee: “The point about the exact language of the target is that people will be offered to have had the vaccine.

“It is not that you might get an offer on the 14th for a vaccine in a couple of weeks’ time; it is that you will have been offered to have had the vaccine by 15 February.”

Matt Hancock announced a new target this week: offering a vaccine to every adult in the UK by the autumn. That could stretch from September to December 21, depending on your definition, and it’s not clear what precise date he has in mind, or whether he envisages all adults getting one dose or two.

In evidence to MPs, Sir Simon Stevens talked about reaching all adults “during the balance of the year”.

Are we on track?

Around 165,000 people were vaccinated on Monday and 224,000 on Tuesday, according to the latest official figures.

Just over 3 million people have now received a first or second dose in the UK, and there are 33 days between January 12 and February 15.

To vaccinate all 13.9 million people by then, we would need to carry out more than 300,000 vaccinations a day – around double the current rate.

The government says that ability of drug companies to supply enough vaccine quickly is the limiting factor in the rollout.

Two companies are making vaccines for the UK: Pfizer and AstraZeneca. The UK has placed its biggest order with AstraZeneca: 100 million doses. So it’s clear that the success of the vaccination programme will depend to a large extent on AstraZeneca’s ability to ramp up vaccine production.

How much AstraZeneca vaccine do we have?

Tom Keith-Roach, the President of AstraZeneca UK, told Parliament’s Science and Technology Committee today that the company had release just over 1.1 million doses of vaccine so far since the rollout began.

He said AstraZeneca was “absolutely on track” to increase supply to 2 million doses every week on average “imminently”, although he would not say how many doses were expected next week.

Even if we reach two million doses a week almost immediately and sustain that rate of production, that may not be enough to hit the government target of having nearly 14 million doses available by 15 February – although we don’t know how much Pfizer is expected to supply before then.

Why is it less than expected?

It’s clear from many statements made by ministers and others that the supply of AstraZeneca has been slower than was expected last year.

Back in May 2020, a government press release talked about the company supplying 30 million doses by September. That fell by the wayside quickly.

On November 4 Kate Bingham, then head of UK Vaccine Taskforce, admitted that early production forecasts had been over-optimistic but said we would “end up with the 100 million doses that we have secured from AZ in the first half of next year”.

On November 27, the government said AstraZeneca expected to have 40m doses ready by March 2021, echoing briefings the company was giving at the time.

At a rate of 2 million doses a week, AstraZeneca will not now come up with 40m doses in the first quarter of this year, or 100m doses in the first half.

Sir Mene Pangalos, Executive Vice President of BioPharmaceuticals Research and Development at AstraZeneca, said today: “Yields were lower than anticipated. We had batch failures, and that’s all part of moving very rapidly as you’re trying to optimise a process.”