The Prime Minister has warned people not to meet their loved ones indoors over Easter, even if they have been vaccinated.
Boris Johnson urged against indoor mixing of different households, warning vaccines do not guarantee "100% protection" from coronavirus.
Socialising indoors remains banned under England's lockdown rules, but groups of up to six, or two households, are now able to meet up outdoors.
As millions plan Covid-compliant Easter weekend celebrations, the PM said the country was not yet at the stage of allowing people to meet indoors.
The earliest date that families and friends could be reunited inside their homes is May 17 according to Mr Johnson's roadmap.
During a Twitter question and answer session, Mr Johnson was asked if people could meet loved ones indoors if they are vaccinated, to which he replied: "I’m afraid the answer is no, because we’re not yet at that stage.
"We’re still very much in a world where you can meet friends and family outdoors under the rule of six or two households.
"And even though your friends and family members may be vaccinated, the vaccines are not giving 100% protection, and that’s why we just need to be cautious.
"We don’t think that they entirely reduce or remove the risk of transmission."
AstraZeneca, the company that partnered with Oxford University on a jab, has said its vaccine has 76% efficacy against symptomatic Covid-19.
Watch ITV News Correspondent John Ray's report on vaccine passports:
The pharmaceutical giant said its vaccine is 100% effective against severe or critical disease and hospital admission due to the virus.
It also has 85% efficacy against symptomatic Covid-19 in patients aged 65 years and over, the British-Swedish firm said.
More than 31 million in the UK have now received a first Covid vaccine dose, as the rollout progresses towards hitting the government’s target of offering a jab to all adults by July.
It comes as the government's potential plan for vaccine passports faces fierce criticism for being "a tool for discrimination, bullying, [and] corruption".
More than 70 MPs, including 40 Conservatives, as well as peers from the House of Lords, have launched a campaign to oppose the move for vaccine passports within the UK.
Labour's Baroness Chakrabarti told ITV News that introducing domestic vaccine passports would lead to discrimination.
The former shadow attorney general said: "Passports are fine for international travel and that kind of travel is a privilege. But crossing the street, as opposed to crossing borders, that's not a privilege. That should be a fundamental right that comes with living in our community.
"Internal passports and internal vaccine passports would be a tool for discrimination, bullying, corruption, segregation in a society which needs to move through this pandemic together."
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