PCR tests for everyone entering the UK will be introduced and all contacts of new variant cases will have to self-isolate, even if fully jabbed.
Mr Johnson said: “Our scientists are learning more hour by hour, and it does appear that Omicron spreads very rapidly and can be spread between people who are double vaccinated.”
He added: “We need to slow down the spread of this variant here in the UK, because measures at the border can only ever minimise and delay the arrival of a new variant rather than stop it all together.”