Results that show the Oxford-AstraZenenca vaccine may reduce the spread of coronavirus have been hailed as "absolutely superb" by the health secretary.

Matt Hancock said the study shows "vaccines are the way out of this pandemic".

It is the first time a vaccine has been shown to reduce transmission of the virus.

The UK has given a first Covid jab to 9.6 million people so far.

The results of the study, which has not yet been formally published, suggest that the vaccine may have a "substantial" effect on transmission of the virus.

It means the jab could have a greater impact on the pandemic, as each person who is vaccinated will indirectly protect other people too.

Mr Hancock called the study "really encouraging" on Twitter, adding that the results were "absolutely superb".

Speaking on BBC Breakfast, he said this latest analysis showing the vaccine reduces transmission would "help us all get out of this pandemic".

The study by the University of Oxford, where the vaccine was developed, measured the impact on transmission by testing for asymptomatic infections, swabbing participants every week in addition to recording when anyone fell ill with Covid-19.

As well as showing an effect on transmission, the study found the vaccine offered 76% effective protection from a single dose for three months.

With no fall in protection during the three-month period, the researchers said the results supported gaps between first and second doses of between four and 12 weeks.

The effectiveness of the vaccine increased with a longer gap of 12 weeks before the booster jab.

When the second dose is given, the study found the level of protection from the Oxford-AstraZeneca vaccine rises to 82%.

In other developments:

• One of the world's largest follow-up Covid studies found almost 90% of people who tested positive for Covid had protective antibodies against the virus six months after their initial infection

• The number of people with coronavirus has changed little in the week to 23 January, the Office for National Statistics says, with virus levels still high in England (one in 55) and level in Scotland (one in 110), Wales (one in 70) and Northern Ireland (one in 50)

Study 'reassures us'

The UK has set itself apart from many other countries by prioritising giving the first dose to as many people as possible, delaying the second jab for about 12 weeks.

The aim is to save more lives by giving some protection to a larger number of people, but the UK has faced criticism from the British Medical Association for following this path with no international support.

Prof Andrew Pollard, chief investigator of the Oxford vaccine trial, said the results supported the UK's approach to delaying the booster shot.

It "reassures us that people are protected from 22 days after a single dose of the vaccine," he says.

The data from this latest trial was drawn before new variants, including the South Africa one, emerged.

Asked how protective the Oxford vaccine could be against new mutations, Dr Pollard said he was anticipating "good protection" against the Kent variant and would publish details "very soon".

On other variants, he told BBC Radio 4's Today programme: "When we look at the new mutations that have been arising in other countries and now also here in the UK - that is the virus trying to escape from human immunity, and that's whether it's from vaccines or from infection.

"I think that's telling us about what's to come, which is a virus that continues to transmit, but hopefully that will be like other coronaviruses that are around us all the time, which cause colds and mild infections.

"We will have built up enough immunity to prevent the other severe disease that we've been seeing over the last year."