Chris Whitty is expected to make a Downing Street announcement today, it is reported.

The Chief Medical Officer for England will be joined by health ministers from all four nations during the address.

Boris Johnson will not be present for the press conference, although it is expected he will make a separate address tomorrow on the government's Covid winter plan.

Professor Whitty's announcement comes after the UK’s four chief medical officers (CMOs) have said children aged between 12-15 should be offered a first dose of the Pfizer/BioNTech vaccine.

It is expected the vaccinations will be given through schools as soon as possible.

The JCVI said Covid-19 presents a very low risk for healthy children and vaccination would only offer a marginal benefit.

But they suggested that the wider issues, such as education, should be taken into consideration and examined by CMOs.

In their advice to the Government, the UK’s CMOs said they were recommending vaccines on “public health grounds” and it was “likely vaccination will help reduce transmission of Covid-19 in schools”.

They added: “Covid-19 is a disease which can be very effectively transmitted by mass spreading events, especially with Delta variant.

“Having a significant proportion of pupils vaccinated is likely to reduce the probability of such events which are likely to cause local outbreaks in, or associated with, schools.

“They will also reduce the chance an individual child gets Covid-19. This means vaccination is likely to reduce (but not eliminate) education disruption.”