Sir Simon Stevens told MPs on Tuesday that second doses at 12 weeks would be prioritised from the vaccine supply.
Questioned on whether numbers of patients coming forward for a second dose from March would slow down rollout of first doses, Sir Simon said: 'First and foremost, those second doses have got to be delivered...we know that that has to be first call on the vaccine available in those weeks. Over and above that, then as we get increasing clarity as to what the available supply will be, that will shape the speed at which we can advance into other groups.'
The NHS chief executive said that the COVID-19 vaccination programme was currently operating on a 'push model' and the NHS was 'pretty much using up each week's vaccine as we get it'. He said the vaccines were being delivered so that each part of the country had enough vaccine to be able to offer over-70s, high-risk patients and health and social care staff their first vaccine.
'For second doses we will be partly moving on to a so-called "pull model" where the local services will be saying "I need this many vaccines next week for my second vaccinations", and then the vaccination team will make those vaccines available to them,' Sir Simon said.
The government is aiming to vaccinate the first four groups on the Joint Committee on Vaccination and Immunisation (JCVI) priority list with their first dose by 15 February.
Sir Simon told MPs there could be a case for the JCVI to review the priority groups that should receive the jab following this initial stage of the programme.
The current JCVI list says that, after the first four groups, those next in line should be over 65s and those aged 16 to 64 with an underlying health condition, effectively those who receive the flu jab each year. This is followed by over 60s, over 55s, then over 50s. The JCVI has not yet made any recommendations past these cohorts.
However, Sir Simon said that after the over-70s, clinically extremely vulnerable and healthcare staff had been vaccinated there was a 'legitimate discussion' to be had on whether the JCVI 'will advise on whether or not there are certain other groups who at that point also receive priority'.
He added: 'People with learning difficulties and autism, certain key public service workers, teachers, the police, will all have to be factored in, in that post-15 February prioritisation decision.'
Sir Simon said that in terms of reducing the number of hospital admissions from COVID it made sense to follow the age cohorts as currently set out by the JCVI. But, he said: 'That's not the only consideration that policy makers legitimately would want to take into account, which is why I think teachers and police and other key public service workers – that will be one of the discussions that will need needs to be had'.
Sir Simon was also asked about how the vaccination campaign would cover hard-to-reach groups and those not registered with GP practices. He said that, alongside community outreach work, the NHS would tell eligible people how they could come forward for vaccination as they approached the end of a particular cohort group.
'Rght now the NHS is saying wait for us to contact you, rather than phoning your surgery, for example. But as we get to the end of each cohort, we will then be saying very clearly, "if you fall into this category and you haven't been vaccinated, then here's how you can come forward and be vaccinated".'
The NHS chief executive also said that in future winters the NHS could be administering a combined flu and COVID jab. He said: 'it would be great if COVID vaccine and flu vaccine ends up being combined into a single vaccine, which we might see, for, if not this winter, then future winters'.