The impact of the Omicron variant on the UK is “highly uncertain” but may require a “very stringent response”, government advisers have said.
The BBC has seen leaked minutes of a meeting of the Scientific Advisory Group for Emergencies held on Monday.
Officials should prepare now for a “potentially significant” wave of infections while data on the variant is collected and analysed, they say.
The government said it will take further action if necessary.
The prime minister said on Tuesday that officials would be “throwing everything” at a campaign to roll out booster jabs to all adults this winter.
The programme was expanded in response to the emerging Omicron variant, which scientists believe could be more infectious than the existing Delta variant of coronavirus.
Omicron wave ‘highly uncertain’
More than 30 scientists attended a video conference on 29 November, led by the government’s chief scientific adviser Sir Patrick Vallance and chief medical adviser Chris Whitty.
Sage meetings are often designed to advise officials and ministers about the possible path of the pandemic in certain circumstances rather than offer up concrete predictions.
The minutes, which have not yet been published but have been seen by the BBC, say that it is “highly likely” that Omicron can escape immunity caused by previous infection or vaccination “to some extent”.
The existing Delta variant is already more resistant to vaccines than the original version of the virus found in Wuhan.
The advisers say that there is not currently any evidence of widespread community transmission of Omicron in the UK, as there has been in parts of South Africa. They say the impact on a country like the UK remains uncertain as it is different in terms of age structure, the numbers previously infected with coronavirus and the level of vaccination coverage.
The scientists believe that booster jabs are likely to provide protection against severe disease, hospitalisation and death from most variants in the short term.
But they note: “Any significant reduction in protection against infection could still result in a very large wave of infections. This would in turn lead to a potentially high number of hospitalisations even with protection against severe disease being less affected.”
Although the size of any future wave remains “highly uncertain”, the scientists say it may be of a scale that requires “very stringent response measures” to avoid unsustainable pressure on the NHS.