Hundreds of thousands of people who were asked to shield earlier this month are being invited for a COVID-19 vaccination.
A further 1.7 million people in England were identified as being at additional risk from the virus and were told to shield last Tuesday.
They were identified by a new algorithm that looks at multiple factors, and were told they would be prioritised for the jab and that it would be offered soon.
About 600,000 of them are now being invited to book a slot at a vaccination centre or with a pharmacy, the NHS said.
The remainder have already had their jabs as they are part of the first priority groups.
People in group five – anybody aged 65 and over – are currently being immunised. Some areas have moved on to group six – adults aged 16 to 64 with underlying health conditions.
The NHS has said invitation letters will now also be going to about 445,000 people aged 64 who have not yet been offered the vaccine.
They are in group seven – all those aged 60 and over.
On Wednesday, the government announced that all adults on the learning disability register will be prioritised to get the vaccine.
They are already part of group six, but care minister Helen Whately confirmed they will all be invited for a vaccine now following a recommendation from the Joint Committee on Vaccination and Immunisation (JCVI), the panel that advises the government on inoculation priority.
Broadcaster Jo Whiley, 55, had been calling for people with learning disabilities to be prioritised after her sister, who has learning disabilities, was admitted to hospital with COVID-19 while the DJ was offered a vaccine.
NHS medical director Professor Stephen Powis has urged anyone in the top priority groups who has not yet been vaccinated that “it is not too late” to come forward for a jab.
Boris Johnson has said all adults in the UK should be offered their first vaccination by 31 July, and everyone over the age of 50 by 15 April.
On Monday, he laid out a roadmap out of lockdown with the hope of lifting all restrictions by 21 June. It depends on how the vaccination programme goes as well as data.