A senior GP has hit out at the extended time between doses of coronavirus vaccinations - branding the move an "unregulated and unlicensed trial".

The government is under pressure to shorten the current 12 week period between the first and second jabs.

Dr Rosie Shire, a member of the Doctors' Association UK, said studies of the Pfizer/BioNTech vaccine show two doses three weeks apart gave 90 per cent immunity.

But she said it is not known if it is as effective if the gap is longer.

The government and health bosses have previously opted to administer a first dose to as many people as possible.

Dr Rosie Shire speaking on Sky News today
Dr Rosie Shire said extending the time between jabs was an 'unregulated and unlicensed trial'

"What really concerns us is we don't know what happens if you don't give that second dose of vaccination after three weeks," Dr Shire told Sky News.

"The fact is that people are being vaccinated now and being put into what is effectively an unregulated unlicensed trial, whereby they're receiving this vaccination on the understanding that they don't know what's going on."

She said three quarters of all people over 80 in the UK have been given the first dose of a vaccine, but added this does not mean they are fully vaccinated.

Yesterday it emerged the British Medical Association has called for the gap to be slashed in half.

NHS staff and key workers receive the coronavirus vaccine
There is currently a 12 week gap between jabs in an effort to provide protection to as many people as possible

A private letter, seen by the BBC, said the current plans of people waiting up to 12 weeks for a second dose - which Health Secretary Matt Hancock said is supported by data from an Israeli study - are "difficult to justify".

It said: "The absence of any international support for the UK's approach is a cause of deep concern and risks undermining public and the profession's trust in the vaccination programme."

However, Public Health England medical director Dr Yvonne Doyle has defended the decision, which she said had been taken on "public health and scientific advice".

A man receives a COVID-19 vaccine, at the vaccination center at the Bournemouth International Centre
More than 5.8 million have received a first jab, latest figures show

"The more people that are protected against this virus, the less opportunity it has to get the upper hand. Protecting more people is the right thing to do," she told the BBC Radio 4 Today programme.

"People will get their second dose. As supplies become available more people will be vaccinated.

"It is a reasonable scientific balance on the basis of both supply and also protecting the most people."

The UK's Joint Committee on Vaccination and Immunisation previously concluded the first dose delivers 89 per cent protection from day 10 after being administered.

However, initial data from a study led by Professor Ran Balicer in Israel found it may be as low as 33 per cent.

Israel is currently leading the way with its inoculation programme, having already given one in four of its population a jab, with a three-week gap between doses.

Figures revealed today by NHS England showed that nearly half a million people were given Covid vaccines in just 24 hours.

It said a total of 5,970,175 Covid-19 vaccinations had taken place in England between December 8 and January 23 a rise of 444,104 on Saturday's figures.

Of this number, 5,529,101 were the first dose of the vaccine, a rise of 443,330 on Saturday's figures, while 441,074 were the second dose, an increase of 774.