It means the Government has met its target of offering jabs to its top nine priority groups, including the clinically vulnerable and health and social care workers, three days ahead of the April 15 target date.
The Joint Committee on Vaccine and Immunisation will shortly set out its advice for the next phase of the programme, expected to begin this week.
It comes as Ireland became the latest country to restrict the AstraZeneca vaccine, saying it should not be given to people under the age of 60, amid concerns over possible links to rare blood clotting.
In the UK, the advice is it should not be administered to those under 30.
The Government said almost 40 million doses of the Pfizer and AstraZeneca vaccines have been delivered since rollout began in December, including 32 million first jabs and more than seven million second doses.
Mr Johnson said they remained on course to offer a first jab to all adults in the UK by the end of July.
“We have now passed another hugely significant milestone in our vaccine programme by offering jabs to everyone in the nine highest risk groups,” he said.
“That means more than 32 million people have been given the precious protection vaccines provide against Covid 19.
“I want to thank everyone involved in the vaccine rollout which has already saved many thousands of lives.
“We will now move forward with completing essential second doses and making progress towards our target of offering all adults a vaccine by the end of July.”
NHS England chief executive Sir Simon Stevens said 19 out of 20 over 50s had now received a first jab.
The announcement comes despite an earlier warning of a “significant reduction in weekly supply” during April, meaning volumes for first doses would be “significantly constrained”.
Throughout the current month, the health service has prioritised second doses of the Pfizer and AstraZeneca vaccines with a record 475,230 people receiving their second jab on Saturday.
Chris Hopson, chief executive of NHS Provider which represents NHS Trusts, said it had been an “incredible achievement”.
“While there is still a way to go with our vaccination programme, we welcome the progress being made, with the jabs due to be rolled out to the over 40s this week and all priority groups now offered a first dose,” he said.
“We urge everyone to take their Covid-19 vaccine when they are offered it.
“We owe a huge debt of gratitude to NHS staff and volunteers on the frontline, as well as health leaders, undertaking this huge logistical challenge to help protect us from the virus.
“As we return to pub gardens and sports activities and make our way back to non-essential shops, we must continue do all that we can to prevent the spread of infection and ensure this lockdown will be the last.”