Public health experts have recommended a version of the Indian Covid variant found in the UK to be made a “variant of concern”, the BBC has been told.
Public Health England (PHE) has been tracking a variant known as B.1.617.2, which appears to have been spreading more quickly in the UK than others.
Scientists believe it is more transmissible than the version of Covid first discovered in Wuhan, China.
A spokesman for PHE said it would not comment on leaked data.
Viruses mutate all the time, producing different versions of themselves. Most of these mutations are insignificant – and some may even make the virus less dangerous – but others can make it more contagious and harder to vaccinate against.
The Kent, South Africa and Brazil strains have all been deemed “variants of concern” in the UK. These versions, along with the India variant, have all undergone changes to their spike protein – the part of the virus which attaches to human cells.
The original India variant – officially known as B.1.617 – was first detected in the country in October.
That version has now been re-characterised as three different subtypes, all with slightly different genetic mutations.
The UK has seen a sharp increase in one version in particular, known as B.1.617.2, which now makes up the majority of all Indian variant cases and appears to be growing faster than other versions.
PHE scientists think with “moderate confidence” that it spreads at least as quickly as the version of the virus first found in Kent last year – known as B.1.1.7 – which is currently dominant in the UK.
But a source has told the BBC there is no evidence this version of the Indian variant is resistant to current vaccines.
It does not feature the E.484K mutation found in the South African variant of the virus, which could help the virus dodge a person’s immune system and may affect how well coronavirus vaccines work.
It is believed that more than 500 cases of B.1.617.2 have now been detected across England with the highest levels in London and the north-west of England.
That would represent a sharp rise from the 202 cases officially recorded by PHE in the UK as of 28 April.
It is not known how many of the current infections in the UK can be linked back to international travel.
However, it is thought there has already been some evidence of “significant” community transmission, mainly linked to workplaces and religions gatherings.
In one cluster at a care home, 14 elderly residents who have all been vaccinated were infected with the variant, the source said. A number needed hospital treatment but not for severe disease, and it is thought all have now recovered.
All current vaccines are thought to offer some degree of protection against variants but can never completely stop all Covid infections, especially among the vulnerable or elderly.
Laboratory work is needed to sequence individual Covid tests and identify specific variants, meaning the latest figures are likely to represent the situation around a week ago.
Figures from the Wellcome Sanger Institute, which analyses positive swabs for different variants, also showed clusters of B.1.617.2 in places including Leicester, Bolton, Nottingham and Blackburn in the week to 24 April.
It comes as seven confirmed cases of the B.1.617.2 variant have been detected in Northern Ireland – the first discovered in the region.
Scientists at Public Health England have now recommended that the B.1.617.2 variant should be formally designated a “variant of concern”, the BBC has been told, with India and the World Health Organization expected to be informed of the change later.
Dr William Welfare, the Covid-19 incident director at PHE, said: “Public Health England is monitoring the situation closely and appropriate public health interventions, including targeted testing and enhanced contact tracing, are being undertaken.”
Government statistics show 127,583 people have now died, up 13 in the latest 24-hour period. In total 4,428,553 people have tested positive, up 2,613 in the latest 24-hour period. Latest figures show 1,289 people in hospital. In total, 34,934,171 people have received their first vaccination and 16,291,719 have had their second dose
The government has previously rolled out increased Covid testing to prevent the spread of outbreaks of more contagious variants – in a process known as surge testing.
Extra tests and enhanced contact tracing is carried out in very specific locations – local authority areas, postcodes or even individual streets.
In April, households in various of areas of Birmingham were asked to take Covid-19 PCR tests after a small number of cases of the South Africa variant were found in the city.
India has said the B.1.617 variant may be linked to a deadly second coronavirus wave that has swept the country in recent weeks.
The country reported a record 412,000 cases in the space of 24 hours on Wednesday, and 3,980 deaths.
The surge in infections has already overwhelmed the healthcare system with hospital beds, oxygen and even crematorium space in short supply, while several states are under localised lockdowns and curfews.