Having both doses of a Covid vaccine is highly effective against hospitalisation from the Delta variant, new Public Health England research shows.

The analysis suggests that the Pfizer-BioNTech vaccine is 96 per cent effective against hospitalisation after two doses.

That goes down slightly to 92 per cent with the Oxford-AstraZeneca vaccine.

These are comparable with vaccine effectiveness against hospitalisation from the Alpha variant.

The news comes as Prime Minister Boris Johnson is set to announce a four-week delay to ending lockdown.

The original date for the fourth and last stage of lifting all legal restrictions on social distancing had been set for June 21.

But but due to the risk posed by the Delta variant and warnings of a third wave being imminent, the government is set to push the end of lockdown back to July 19.

Prime Minister Boris Johnson is expected to announce a four-week delay to ending lockdown

Further work remains underway to establish the level of protection against mortality from the Delta variant.

But the body did say that unvaccinated people have twice the risk of hospital admission with the Delta variant as the Alpha (Kent) variant.

And among those who are vaccinated, 12 people in every 100 may end up in hospital with Delta compared with eight for Alpha.

But the level of protection against mortality offered by the jabs for the Delta variant is still expected to be high.

The analysis included 14,019 cases of the Delta variant – 166 of whom were hospitalised – between 12 April and 4 June, looking at emergency hospital admissions in England.

PHE has previously published analysis showing that one dose is 17 per cent less effective at preventing symptomatic illness from the Delta variant, compared to Alpha, but there is only a small difference after two doses.

Health and Social Care Secretary Matt Hancock said: “Our UK vaccination programme continues at pace and has already saved thousands of lives. It is our way out of this pandemic.

A Downing Street press conference was shown numbers of Alpha and Delta coronavirus cases

“This evidence of the effectiveness of two doses against variants shows just how crucial it is to get your second jab.

"If you have had your first dose but haven’t booked your second yet – please do so. It will help save lives and boost us on the road to recovery.”

Dr Mary Ramsay, Head of Immunisation at PHE, said: “These hugely important findings confirm that the vaccines offer significant protection against hospitalisation from the Delta variant.

“The vaccines are the most important tool we have against COVID-19. Thousands of lives have already been saved because of them.

“It is absolutely vital to get both doses as soon as they are offered to you, to gain maximum protection against all existing and emerging variants.”

Vaccines Minister Nadhim Zahawi said: “It is extremely encouraging to see today’s research showing that vaccines are continuing to help break the link between hospitalisation and the Delta variant after one dose, and particularly the high effectiveness of two doses.

“If you’re getting the call to bring forward your second dose appointment - do not delay - get the second jab so you can benefit from the fullest possible protection.”

Separate PHE analysis indicates that the COVID-19 vaccination programme has so far prevented 14,000 deaths and around 42,000 hospitalisations in older people in England, up to 30 May.