"The vaccine rollout has been very impressive, and thanks to everybody who's been involved in it, but what we don't know is exactly how strong our fortifications now are, how robust our defences are against another wave,".
"I am hopeful, I don't see anything in the data right now that would cause us to deviate from the roadmap, but we have got to remain humble in the face of nature and we have to be prepared to do whatever it takes to protect the British public,"
On Monday, there will be a smaller change, allowing groups of 6 to meet up outside. Foreign travel will be banned until at least May 17, which is also the earliest date indoor hospitality and performance venues might re-open.
Although Johnson has outlined dates at which he plans to ease restrictions, he has been clear that it is "data, not dates" which will determine whether the unlocking can proceed to schedule.
"One thing I would say is that we're on the side of openness. That's where we are. I don't want to see blockades of vaccines or medicines, I don't think that's the way forward either for us or any of our friends," Johnson said in a pooled interview for broadcasters.
He also denied a report that he said capitalism and greed gave Britain its success in vaccinating its population.
"We will take a decision, no matter how tough, to interrupt that trade, to interrupt those flows, if we think that it is necessary to protect public health and to stop new variants coming in," Johnson said, however.
"The vaccine is a national success story and our way out of this pandemic," said Hancock, adding that he was "delighted".
British Prime Minister Boris Johnson got his first vaccine dose on Friday, receiving AstraZeneca's shot - which several European countries had temporarily stopped using earlier this week over safety fears.
Dominic Cummings, Johnson's senior adviser until November last year, said Britain's more recent success in rolling out a rapid vaccine programme was a result of a decision to take vaccine procurement out of the ministry's hands.
The health ministry was "just a smoking ruin in terms of procurement and PPE and all of that", he said.
"As the MHRA (Britain's Medicines and Healthcare Products Regulatory Agency) has said, blood clots occur naturally but there is no evidence that they are any more likely to occur following vaccination, so as such there's no evidence of any causal link between blood clots and the AZ vaccine," he told reporters.
Addressing parliament, Johnson used his introductory comments to "correct" Michel's suggestion and asked the chamber to join him in rejecting it.
We can also be proud of the support the UK has given to the international COVID response ... I therefore wish to correct the suggestion from the European Council president that the UK has blocked vaccine exports.