Pushing back so-called Freedom Day to July 19 will mean that the NHS can vaccinate “many more people”, NHS Providers said as it welcomed the “cautious” approach.
It will also mean that there is “less pressure” on hospitals which are still recovering from the effects of the pandemic.
Meanwhile, the NHS Confederation said health leaders will be “relieved” at the delay.
Chris Hopson, chief executive of NHS Providers, said that a cautious approach “is prudent”.
He said: “There is welcome increasing evidence that, for this pattern of variants, vaccines are breaking the chain between COVID-19 infections and the high levels of hospitalisations and mortality we saw in previous waves.
“A delay of four weeks will enable the NHS to do two important things. It will enable us to confirm the extent to which vaccines have broken the chain between infections and hospitalisations and deaths. And, crucially, it will enable us to vaccinate many more people with double doses and a period of protection build up.
“It will also mean less pressure on hospitals at a point when they are very busy recovering care backlogs and dealing with increased demand for emergency care with significantly reduced capacity, due to the need to prevent the spread of COVID-19 in hospitals.
“So trust leaders will welcome the decision taken today, for operational reasons. But they will also understand the impact of continuing lockdown measures on people’s lives, mental health and on the economy.
”Vaccines will enable us to exit this current pandemic soon. But we must all understand that the virus will be with us for a long time yet. So our next task will be to discuss what the NHS, and we as a nation, need to do to live with the virus longer term. That debate has barely started.”
Matthew Taylor chief executive of the NHS Confederation, added: “Health leaders will be relieved that the Prime Minister has listened to their warnings and extended the current lockdown restrictions.
“With rising hospitalisations, over 7,700 cases of coronavirus being confirmed every day in England, around half of the adult population not having been fully vaccinated yet, and over one million people believed to have ‘Long Covid’, opening up further before 21 June would have been dangerous.
“Our members are committed to using this extra time to vaccinate as many adults as they can so that we can protect our population and support the NHS to continue to restore its services for patients.
“However, if the data continues to show that the Covid situation has not improved come 19 July, the Government has to be prepared to act decisively again and if needed, slam the brakes down further.”
BMA chair of council Dr Chaand Nagpaul said: “I am glad the Government has listened to the BMA and others like us who, in recent days, made clear the need for the current restrictions in England to remain in place for a few more weeks.
“As the Prime Minister and chief medical officer said, the number of cases in England has gone up 64% compared with the previous week, and we know that the highly transmissible Delta variant accounts for the vast majority of those infections.”
Dr Nagpaul added: “We are, without doubt, in a phase where cases of the virus are spiralling, but the data we have still doesn’t yet show the full impact of this or of the easing of restrictions on May 17.
“Furthermore, the more people who have the virus, the more likely it is that new variants of concern will emerge and numbers of those with longer term ill health following infection will increase.
“So, it is important to do whatever we can to avoid high levels of virus circulating in the community.”