A subvariant of Omicron that is growing quickly in Britain is not more vaccine-resistant than its ancestor strain, reassuring real-world data shows.
UK health officials said booster jabs may even offer slightly better protection against BA.2, which is believed to be more infectious than Omicron.
The subvariant makes up at least one in 125 new cases in England and it is outcompeting the original Omicron in some corners of Europe.
There were fears it may be able to slip past vaccine immunity more easily than Omicron, which would explain its evolutionary edge.
But an analysis by the UK Health Security Agency found two and three vaccine doses work just as well against both strains.
A booster was found to give 70 per cent protection against symptomatic infection from BA.2, compared to 63 per cent with the original Omicron.
Waning immunity from two doses only offers 13 per cent protection against the new subvariant, slightly more than the 9 per cent for its parent variant.
Immunity against severe disease is expected to be even higher but it takes several weeks for enough people to fall ill with a new strain to accrue the data.
It came as Sajid Javid, the Health Secretary, said it was the 'professional duty' of every NHS worker to get vaccinated ahead of new rules coming in next week.
Frontline staff must have their first jabs by February 3 to make sure they are double-vaccinated by April 1 or they will be sacked or deployed into backroom roles.
Meanwhile, separate official figures showed pregnant women who get vaccinated are not at a higher risk of complications, allaying long held concerns about jab safety in expectant mothers.
A booster was found to give 70 per cent protection against symptomatic infection from BA.2, compared to 63 per cent with the original Omicron. Waning immunity from two doses only offers 13 per cent protection against the new subvariant, slightly more than the 9 per cent for its parent variant
The above shows the number of BA.2 lineages detected by the Sanger Institute — one of the UK's largest Covid surveillance centres — over the week to January 8 (left) and January 15 (right) broken down by local authority
Pictured above is the data from the Sanger Institute — one of the largest Covid surveillance centres in the UK — which shows BA.2 has now outpaced Delta
A booster jab was shown to be 88 per cent effective at preventing people ending up in hospital with the original Omicron.
Two doses initially give 72 per cent protection, although after six months that protection fades to 52 per cent.
