© Liverpool ECHONHS Get Boosted Now message
The screens read 'get boosted now' and have official government and NHS branding logos on them.
The messages appear on a monitor that is being carried around on the shoulders of those carrying them.
They have been spotted after the Health Secretary, Sajid Javid, confirmed that no further coronavirus restrictions would be introduced in England before the new year.
However Boris Johnson has urged people in England to 'continue to act cautiously.'
In a series of tweets the Prime Minister said: "We will continue to monitor the data carefully, but there will be no new restrictions introduced in England before the New Year.
"However, I would urge everyone to continue to act cautiously given the rising number of Omicron cases.
"Most importantly I urge everyone to get their first, second or booster jab without delay to protect yourselves and your loved ones."
Mr Javid said "people should remain cautious" and urged those marking the start of 2022 to consider testing themselves beforehand and to celebrate outside, with the Omicron variant growing so fast that it accounts for 90% of all new Covid-19 cases.
Comment: How many deaths does it account for Mr. Javid?
Mr Javid told broadcasters on Monday: "We look at the data on a daily basis - that hasn't changed over the Christmas period.
"But there will be no further measures before the new year. Of course, people should remain cautious as we approach New Year's celebrations.
"Take a lateral flow test if that makes sense, celebrate outside if you can, have some ventilation if you can.
"Please remain cautious and when we get into the new year, of course, we will see then whether we do need to take any further measures, but nothing more until then, at least."
Government data shows that a record 113,628 cases were recorded in England on Christmas Day, although the highest number by specimen date - marking when the test was taken - was December 22, when 121,539 people took a test which gave a positive result.
The final UK figure for reported cases on Christmas Day is likely to be higher still as the data published on Monday is incomplete due to holidays, and does not include any data for Scotland and Northern Ireland.
England will remain under the UK Government's Plan B rulebook until at least January 1, with guidance to work from home, mask wearing in shops and other public settings, and Covid passes to gain entry to large events.
Comment: We live in a clown world! The government and the NHS are pushing the 'Get boosted now' message hard! On boxing day text messages were sent out to people in the UK strongly urging them to get the booster shot, although the message drew ire and ridicule on social media from some:
Newspapers and advertising stands were also flooded with the message: