Prof Whitty also said that ministers were attempting to balance the economic, social and health impacts of restrictions, and that the Government may change their advice if vaccine effectiveness turned out to be less than hoped.

But he said that vaccines appeared to be holding up well against omicron and that new data was showing that boosters may even be preventing transmissibility and infection from the new variant.

“Antibody response is much less effective against this variant than it was against delta and alpha and the original Wuhan strain. That is likely to translate into its ability to reduce infection,” he said. 

“Lots of people are getting reinfected with omicron who previously have been vaccinated or what vaccine and natural infection.

“I think most people think on the positive side, that there will be some preserved immunity particularly on the non-antibody side, such as t-cells., therefore it is likely someone who has one or two vaccines already will have some protection and with a booster considerably more protection against hospitalisation and death.

“It does look as if boosters restore some of the ability to actually reduce infection and transmission, at least for a period of time.”