UK scientists probe Delta subvariant as more than 49,000 new Covid cases reported

Public health body says early evidence shows AY.4.2 could be more transmissible

Britain's Prime Minister Boris Johnson speaks to the media as he visits a Covid-19 vaccination centre at Little Venice Sports Centre in London. AFP

British health officials on Friday said they were formally looking into a subvariant of the Delta strain of the coronavirus, after it was seen in a growing number of cases.

The UK Health Security Agency (UKHSA), a public health protection body, said AY. 4.2, which was last week detected in 6 per cent of cases, had been “designated as a variant under investigation” but not yet a “variant of concern".

“The designation was made on the basis that this sub-lineage has become increasingly common in the UK in recent months and there is some early evidence that it may have an increased growth rate in the UK compared to Delta,” the agency said.

“More evidence is needed to know whether this is due to changes in the virus's behaviour or to epidemiological conditions,” it added.

The UKHSA said the Delta variant was “overwhelmingly dominant” in Britain, accounting for 99.8 per cent of all cases.

But as of October 20, there have been 15,120 cases of the subvariant AY. 4.2, which was first detected in July, as coronavirus restrictions were lifted across the country.

“While evidence is still emerging, so far it does not appear this variant causes more severe disease or renders the vaccines currently deployed any less effective,” the agency added.

Britain is currently battling the second-highest infection rate in the world, behind the US, with more than 50,000 cases recorded on Thursday — the highest since July.

Not all commuters on the Underground in London choose to wear masks. UK government ministers are under pressure to implement 'Plan B' winter measures to address rising Covid-19 case numbers and a faltering booster vaccine programme. AFP

Health workers at a Covid-19 PCR test centre in London. Britain's daily coronavirus case numbers and the seven-day rolling average reached their highest level in three months in October. EPA

A man receives a Covid-19 vaccine at Regent Pharmacy in Northampton. There are concerns over a sluggish booster shot programme for over-50s and low uptake of vaccines among 12 to 15-year-olds. Reuters

Britain's Health Secretary Sajid Javid with UK Health Security Agency chief executive, Dr Jenny Harries, during a press conference at Downing Street. Getty Images

The National Covid Memorial Wall in London. Under UK Prime Minister Boris Johnson’s winter plan announced in September, Plan B would include a return to working from home for many, mandatory mask-wearing in some settings and vaccine certificates required at large indoor gatherings. Reuters

A demonstration in Parliament Square, London, against Covid-19 vaccine passports and British government restrictions to curb the spread of coronavirus. AP Photo

Passengers on a London Underground train on the Jubilee Line, where face coverings are required to be worn. AP Photo

Bus passengers in London. Masks are not mandatory in indoor settings such as shops, restaurants and bars in England. AP Photo

A section of the National Covid Memorial Wall – a dedication of thousands of hand-painted hearts and messages commemorating victims of the Covid-19 pandemic. Reuters

An NHS Covid-19 vaccination campaign advertisement near a housing block in London. Reuters

On Friday, about 50,000 new cases were added, and 180 deaths within 28 days of a positive test, taking the overall toll since the start of the outbreak to 139,326.

High levels of infection among school-age children are said to be responsible for the soaring rates and have prompted calls for some contingency measures to be reintroduced.

Health Secretary Sajid Javid said this week that cases could hit 100,000 a day, as a new advertising blitz was launched to encourage the take-up of booster and flu shots.

Concern has been raised about waning immunity levels, given that Britain started its vaccination campaign in December last year, before many other countries.

But the government is resisting calls for masks to be worn in crowded indoor spaces again, even as health officials said it could help cut close-contact transmission and ease the burden on hospitals over the coming winter months.

Ministers say vaccination rates have helped to cut the link between hospital admissions for more serious cases of Covid and deaths.