A subvariant of the Covid Delta strain could be more infectious than its ancestor, experts warned today after data revealed the proportion of cases linked to the strain has doubled in a month.
AY.4.2, as it is currently known to scientists, made up almost 10 per cent of all infections in England in the fortnight ending October 9. Virus-trackers at the Wellcome Sanger Institute, which sequences thousands of Covid samples every week, say its prevalence stood at just four per cent in mid-September.
Academics estimate it may be up to 15 per cent more transmissible than the original Delta, which rapidly became dominant in Britain in the spring before taking off worldwide.
The subvariant has been detected in almost every part of the country and it has been linked with up to 60 per cent of positive tests sampled sequenced in Adur, West Sussex.
Some 45 different sub-lineages of the variant — which was first spotted in India and is thought to be the most transmissible strain of Covid — have been recorded so far.
No10 is keeping a close eye on AY.4.2 but said there is ‘no evidence’ that it spreads more easily. Boris Johnson’s official spokesperson today warned the Government ‘won’t hesitate to take action if necessary’.
It comes amid spiralling cases in the UK, which have shot up to almost 50,000 yesterday in a three-month high.
Experts suggested AY.4.2 may be partly to blame, along with return of pupils to classrooms from August and workers to offices.
SAGE fears there will be a fourth wave by the end of the year that will cripple the NHS.
Ministers are overseeing a rollout of booster jabs to over-50s, healthcare workers and the immunosuppressed to protect the health service as much as possible.
But experts have warned the jabs are being dished out too slowly, with 5million vulnerable adults eligible for a third dose yet to receive it, as the country moves into the colder months and faces the double threat of increasing case numbers and flu.
SAGE adviser ‘Professor Lockdown‘ Neil Ferguson, an epidemiologist at Imperial College London, today insisted it was ‘critical we accelerate’ the booster drive to give ourselves the best chance of avoiding having to bring back curbs.