Just over half of the known Omicron cases in England were caught by peope who had had two Covid jabs, health officials have said.
New analysis from the UK Health Security Agency shows 12 of the 22 cases which had been confirmed by November 30 occured in fully vaccinated individuals.
Most of the 12 cases had only had their second dose within the previous 28 days, which is approximately how long it takes for a jab to reach full effectiveness.
The number of known cases in the UK is also too small to draw any conclusions by scientific standards. No Omicron patients in hospital have died, although the officials added that it’s too early to judge the extent to which cases are leading to severe illness.
But early data from South Africa, where Omicron is now the dominant strain, suggests it is effective at re-infecting people who have immunity to Covid.
A leading microbiologist tracking the country’s outbreak said the strain does not appear to be more transmissible than the Delta variant, which fuelled the second wave last winter.
Speaking at a World Health Organisation briefing, Anne von Gottberg said: ‘Previous infection used to protect against Delta but now with Omicron that doesn’t seem to be the case.’
People reinfected with Omicron were nonetheless presenting with relatively mild symptoms, she added.
Experts including a top South African science adviser said Prof von Gottberg’s findings suggest that the variant may be better at infecting vaccinated people than older strains but is not more likely to cause them serious illness.
The Guardian reports that some scientific advisers are privately calling for Boris Johnson to reimpose work-from-home guidance until Christmas.
Minutes of the latest Sage meeting, released today, said: ‘Even if measures are introduced immediately, there may not be time to fully ascertain whether they are sufficient before decisions are needed on further action.
‘The situation could develop quickly over the coming weeks and decision-makers may need to act while there is still a high level of uncertainty including considering the potential need for stringent response measures.’
Johnson has said the UK’s response is currently focused on accelerating the booster jab rollout and measures restricting travel.
Bookings for booster jobs will open ‘as soon as possible and no later than December 13’, NHS England added on Friday.
It said the jabs would be delivered ‘in descending age groups, with priority given to the vaccination of older adults and those in a Covid-19 at-risk group first’.
The rollout is expected begin earlier if the move is approved ahead of schedule by the UK Health Security Agency.
NHS England also confirmed there were ‘no supply challenges’ with stocks of Moderna or Pfizer booster jabs.
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