London, Mar 9 (IANS): As millions of children returned to classrooms across England, UK Prime Minister Boris Johnson said that the increased risk of coronavirus transmission is "inevitable".

"We do accept, of course, there will be increased risk of transmission, that's inevitable," Johnson said at a press briefing at Downing Street on Monday.

But he added that "the greater risk is keeping children out of school longer", reports Xinhua news agency.

As part of Johnson's long-anticipated "roadmap" to exit the lockdown, schools reopened on Monday morning

The reopening of schools is the first part of the four-step plan, which Johnson said on February 22 was designed to be "cautious but irreversible".

Under the guidance, two people are allowed for recreation in an outdoor public space such as a park, which means they would be allowed to sit down for a coffee, drink or picnic.

England is expected to see all legal social restrictions being removed from June 21.

At Monday's briefing, Johnson said the government can take the first step of easing lockdown with "confidence" because a third of the entire British population has now been vaccinated.

"At all times, we will be driven by the data," he added.

Joining Johnson at the briefing, Deputy Chief Medical Officer for England Jenny Harries acknowledged the impact of opening schools on the virus transmission.

"We do expect there to be an impact on R, but education is of critical public health importance," she said, referring to the coronavirus reproduction number.

More than 22.3 million people in Britain have been given the first jab of a coronavirus vaccine, according to the latest official figures.

Still, Johnson urged continued vigilance with the public as infections remain high.

"With the number of patients being admitted to hospital with Covid still eight times higher than the lows of last summer, it's more vital than ever to follow the rules."