BORIS Johnson tonight revealed the four key numbers that will determine if England needs more severe restrictions brought in.
He listed the vital figures that would either see Brits plunged further into lockdown, or brought out of measures to curb the spread of Omicron.
The Prime Minister said: "[We will be] guided by the hard medical data around four – efficacy of vaccines, severity of Omicron, speed or spread and rate of hospitalisations.
"We will monitor the data and keep it under review and we need to be humble in the face of the virus.
"As soon as it becomes clear boosters are capable of holding Omicron and we have boosted enough then we will be able to move forward as before."
At a gloomy press conference the PM pulled the trigger on the Government's Plan B to tackle the rising tide of Omicron cases ripping across Britain.
He announced he was toughening the rules as scientists warned the NHS could be swamped by 1,000 daily patients infected with the super-strain.
Most read in Health
Watch Boris' Plan B announcement LIVE as PM triggers vaccine passport plan
Pfizer booster jab DOES protect against Omicron variant, says vaccine boss
Doctors warn of 'unusual' symptom in kids with Omicron Covid variant
Boris set to introduce Plan B as Sage warns Omicron could hospitalise 1,000-a-day